21990813 Automotive Heating Cooloing Systems

8/8/2019 21990813 Automotive Heating Cooloing Systems

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climate contvolsystems

refrigeration anheating - operationdiagnosis, and servicself-study stude

reference bollllnllllllllllllllllllllllllllllllllllllllllllllIlllllllll/FCS-12357~REF COURSE CODE: 35SOORDER NUMBER: FCS-12357-RFord Customer Service Division


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IMPORTANT SAFETY NOTICEAppropriate service methods and proper repair procedures are essential for the safe, reliable operation of all motor vehicles,as well as the personal safety of the individual doing the work. This manual provides general directions for accomplishingservice and repair work with tested, effective techniques. Following them will help assure reliability.There are numerous variations in procedures, techniques, tools and parts for servicing vehicles, as well as in the skill of theindividual doing the work. This manual cannot possibly anticipate all such variations and provide advice o r cautions as to each.Accordingly, anyone who departs from instructions provided in this manual must first establish that he compromises neitherhis personal safety nor the vehicle integrity by his choice of methods, tools or parts.As you read through the procedures, you will come across NOTES, CAUTIONS, and WARNINGS. Each one is there,for aspecific purpose. NOTES give you added information that will help you to complete a particular procedure. CAUTIONS aregiven to prevent you from making an error that could damage the vehicle. WARNINGS remind you to be especially careful inthose areas where carelessness can cause personal injury. The following list contains some general WARN INGS that youshould follow when you work on a vehicle.l Always wear safety glasses for eye protection. l To prevent serious bums, avoid contact with hot metall Use safety stands whenever a procedure requires you to parts such as the radiator, exhaust manifold, tail pipe,be under the vehicle. catalytic converter and muffler.

ll Be sure that the ignition switch is always in the OFF Do not smoke while working on the vehicle.position, unless otherwise required by the procedure. l To avoid injury, always remove rings, watches, loosel Set the parking brake when working on the vehicle. If you hanging jewelry, and loose clothing before beginning tohave an automatic transmission, set it in PARK unless workon avehicle. Tie long hair securely behind your head.instructed otherwise for a specific service operation. If you l Keep hands and other objects clear of the radiator fan

have a manual transmission it should be in REVERSE blades. Electric cooling fans can start to operate at any(engine OFF) or NEUTRAL (engine ON) unless instructed time by an increase in underhood temperatures, evenotherwise for a specific service operation. though the ignition is in the OFF position. Therefore, carel Operate the engine only in a well-ventilated area to avoid should be taken to ensure that the electric cooling fan isthe danger of carbon monoxide. completely disconnected when working under the hood.l Keep yourself and your clothing away from moving partswhen the engine is running, especially the fan and belts.

The recommendations and suggestions contained in this manual are made to assist the dealer in improving his dealership parts and/or service department operations. These recommendations and suggestions do not supersede or override the provisions of theWarranty and Policy Manual, and in any cases where there may be a conflict, the provisions of the Warranty and Policy Manualshall govern.The descriptions, testing procedures, and specifications in this handbook were in effect at the time the handbookwas approvedfor printing. Ford Motor Company reserves the right to discontinue mode ls at any time, or change specifications, design, ortesting procedures without notice and without incurring obligation. Any reference to brand names in this manual is intendedmerely as an example of the types of tools, lubricants, materia ls, etc. recommended for use. Equivalents, if available, may beused. The right is reserved to make changes at any time without notice.

WARNING: Many brake linings contain asbestos fibers. When working on brake components, avoid breathing the dust. Breathingthe asbestos dust can cause asbestosis and cancer.Breathing asbestos dust is harmful to your health.Dust and dirt present on car wheel brake and clutch assemblies may contain asbestos fibers that are hazardous to your health whenmade airborne by cleaning with compressed air or by dry brushing.Wheel brake assemblies and clutch facings should be cleaned using a vacuum cleaner recommended for use with asbestos fibers.Dust and dirt should be disposed o f in a manner that prevents dust exposure, such as seated bags. The bag must be labeled perOSHA instructions and the trash hauler notified as to the contents of the bag.If a vacuum bag suitable for asbestos is not available, cleaning should be done wet. lf dust generation is still possible, techniciansshould wear government approved toxic dust purifying respirators.OSHA requires areas where asbestos dust generation is possible to be isolated and posted with warning signs. Only techniciansconcerned with performing brake or clutch service should be present in the area.

Copyright 0 1995 Ford Motor Company Produced and Coordinated byTechnical Service Support OperationsFord Customer Service DivisionNovember 1995


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SERWCE STMDARDS

rDealer-to-Custorner Service Standards:1. Appointment available within oneday of the customers requestedservice day.2. Write-up begins within four minutesof arrival.3. Service needs courteously identified,accurately recorded on RepairOrder, and verified with customer.

4. Vehicles serviced right on thefirst visit.5. Service status provided within oneminute of inquiry.6. Vehicle ready at agreed upon time.7. Thorough explanation of work done,coverages and changes.

These seven service standards provide u process and product value that arecompelling reasons for owners to purchase and repurchase Ford or Lincoln-Mercuryproducts. These standards also help fo attract new owners through favorabletestimonials and improved owner satisfaction.Standard 4Fix It Right the First Time, on Time.The technician is the most important player when it comes to Standard #4.WhyCustomers tell us Fixing It Right the First Time, on Time is one of the reasons they woulddecide to return to a dealer to buy a vehicle and get their vehicles serviced.Technician TrainingIt is our goal to help the technician acquire all of the skills and knowledge necessary toFix it Right the First Time, on Time. We refer to this as competency.Technicians RoleAcquire the skills and knowledge for competency in your specialty viag&T New Model

- Self Study - Self Study- Ford Multimedia Training (FMT) - Instructor Led- Instructor LedThe BenefitsThe successful implementation of standards means- Satisfied customers- Repeat vehicle sales- Repeat service sales- Recognition that Ford and Lincoln/Mercury technicians arethe Best in the Business

@ printed on recycled


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INTRODUCTION ............................................................................................................................. Intro-lCOURSE DESCRIPTION FOR SELF-STUDY LEARNERS.. .................................................... intro-2TECHNICIANS COURSE OBJECTIVES .................................................................................. intro-2CLIMATE CONTROL CURRICULUM ........................................................................................ Intro-2PURPOSE OF CLIMATE CONTROL ........................................................................................ Intro-5LESSON 1: PRINCIPLES OF HEAT TRANSFER .............................................................................. 1-TYPES OF HEAT.. .......................................................................................................................... l-2THE SIX HEAT TRANSFER PRINCIPLES.. ................................................................................... I-5PRINCIPLE ONE ............................................................................................................................ I-5PRINCIPLE TWO.. .......................................................................................................................... 1-PRINCIPLE THREE ........................................................................................................................ l-7PRINCIPLE FOUR .......................................................................................................................... 1-PRINCIPLE FIVE ............................................................................................................................ 1-PRINCIPLE SIX ............................................................................................................................ l-1 PROGRESS CHECK ONE ........................................................................................................... l-1 LESSON 2: AIR CONDITIONING OPERATION ................................................................................. 2-FIXED ORIFICE TUBE SYSTEM.. .................................................................................................. 2-HIGH AND LOW PRESSURE SIDES ........................................................................................... 2-1REFRIGERATION CYCLE.. .......................................................................................................... 2-1THERMOSTATIC EXPANSION VALVE SYSTEM ............ ............ ........... ............ ........... ............ . 2-l PROGRESS CHECK TWO.. ......................................................................................................... 2-1LESSON 3: REFRIGERANTS ............................................................................................................. 3-ENVIRONMENTAL CONCERNS.. .................................................................................................. 3-EFFECTS OF CHLOROFLUOROCARBONS.. ............................................................................... 3-THE MONTREAL PROTOCOL AND CLEAN AIR ACT .................................................................. 3-R-l 34a REFRIGERANT SYSTEMS ............................................................................................... 3-REFRIGERANT OILS ..................................................................................................................... 3-LESSON 4: REFRIGERANT SAFETY AND CLUTCH CONTROL DEVICES .................................... 4-

REGULATING REFRIGERATION PRESSURE ............................................................................. 4-A/C CYCLING PRESSURE SWITCH ............................................................................................. 4-THERMOSTATIC DE-ICING SWITCH ........................................................................................... 4-A/C PRESSURE CUT-OFF SWITCH ............................................................................................. 4-A/C PRESSURE TRANSDUCER ................................................................................................... 4-HIGH PRESSURE RELIEF VALVE ................................................................................................ 4-LOW PRESSURE RELIEF VALVE ................................................................................................. 4-PROGRESS CHECK THREE ......................................................................................................... 4-LESSON 5: HEATING SYSTEM OPERATION ................................................................................... 5-HEATER HOSES ............................................................................................................................ 5-HEATER CORE .............................................................................................................................. 5-BLOWER MOTOR (FAN) ................................................................................................................ 5-WATER VALVE (SOME VEHICLES) .............................................................................................. 5-HEATING CYCLE ........................................................................................................................... 5-PROGRESS CHECK FOUR ........................................................................................................... 5-

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LESSON 6: INTRODUCTION TO DIAGNOSIS .................................................................................. 6-lSECTION DESCRIPTION.. ............................................................................................................. 6-2SYMPTOM-TO-SUBSYSTEM-TO-COMPONENT-TO-CAUSE DIAGNOSTICS ............................ 6-2DIAGNOSTIC PROCEDURE .......................................................................................................... 6-4TYPICAL CLIMATE CONTROL CUSTOMER CONCERNS/TECHNICAL SYMPTOMS/POSSIBLE SUBSYSTEMS/COMPONENTS AND CAUSES ...................................................... 6-6PROGRESS CHECK FIVE ........................................................................................................... 6-13LESSON 7: REFRIGERATION TESTING AND SERVICE ................................................................. 7-ICONDITIONAL TESTING REQUIREMENTS ................................................................................. 7-2DISCHARGE AIR TEMPERATURE TEST ..................................................................................... 7-3COMPRESSOR CLUTCH CYCLE TIME ........................................................................................ 7-4REFRIGERANT LINE PRESSURE TESTING ................................................................................ 7-7PRESSURE TESTING THERMOSTATIC EXPANSION VALVE SYSTEMS ............................... 7-l 2LEAK TESTING ............................................................................................................................ 7-12REFRIGERANT RECOVERY AND RECHARGING ..................................................................... 7-l 5REPLACING COMPONENTS AND REFRIGERANT OIL ............................................................ 7-21A/C SYSTEM FILTERING.. ........................................................................................................... 7-23RETROFITTING.. .......................................................................................................................... 7-26

A/C SYSTEM FLUSHING ............................................................................................................. 7-31PROGRESS CHECK SIX ............................................................................................................. 7-36LESSON 8: HEATING SYSTEM TESTING AND SERVICE ............................................................... 8-lHEATER CORE PRESSURE TESTING ......................................................................................... 8-2THERMOSTAT TESTING ............................................................................................................... 8-2COOLANT MIXTURE, LEVEL AND CONDITION.. ......................................................................... 8-3DRIVE BELTTENSION .................................................................................................................. 8-3AIR BLEEDING ............................................................................................................................... 8-3PROGRESS CHECK SEVEN ......................................................................................................... 8-4REVIEW QUESTIONS ........................................................................................................................ R-lj?,PPENDlX A ....................................................................................................................................... A-lGLOSSARY . . . .*............ ....... . . G-l

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This course has two main goals. The first goal isto introduce you to the basic principles used inFord, Lincoln and Mercury climate controlsystems. The second goal is to instill anunderstanding of the symptom-to-subsystem-to-component-to-cause diagnostic sequence. Asyou learn new information, try to relate the newknowledge to the climate control system as awhole. Think about the cause and effectrelationship between components andsubsystems. Understanding the cause and effectrelationships will assist you in diagnosis. Thescope of this course includes information that isrelated to basic refrigeration and heatingsystems. Although information relating to airmanagement and control systems may bementioned, it is beyond the scope of this courseto cover air management and control systems indepth. Please refer to the Air Management andControl Systems Self-Study Course.Some of the aspects that are covered in thiscourse include:I Sources of vehicle heatn Principles of heat transferq Basic air conditioning operationN RefrigerantsII Basic heating system operationW Symptom-to-subsystem-to-component-to-cause diagnosticsq Refrigeration system diagnosisn Refrigeration system servicen Retrofitting refrigeration systemsn Heating system diagnosis

Introduction

Although you may be familiar with some of thesetopics, it is essential that you, as a professionalclimate control technician, have a thoroughunderstanding and mastery of this information.This is necessary to diagnose and service notonly the basic heating and air conditioningcomponents, but the latest electronic automatictemperature control (EATC) systems as well.Why TrainingLets state a few facts:

1. Customers bring vehicles to the dealershipbecause they want the best service pos-sible.2. Customers expect a dealership to fix it rightthe first time.3. Customers understand that you get whatyou pay for. Therefore, they are willing topay the extra money at the dealership foryour professional services.

So, how do you live up to the customersexpectations so that they will continue to haveyou service their vehicle? The answer iscontinuous training. Training allows you to gainefficiency in your specialty area. Efficiencymakes you an asset to the customer, the dealerand yourself. Training promotes job security andallows you to learn the latest and greatesttechnology and service procedures. Which, bythe way, means more money in your pocket andrecognition for superior service.

Intro- 1


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COURSE DESCRIPTION FORSELF-STUDY LEARNERSThis Training Reference Book is designed foruse as part of a self-study training program. It isa self-paced program, which means you canallow as much time as you need to learn theinformation in each section. A videotape hasbeen developed to accompany this book. Thevideotape provides information that can best bepresented through visual means.Progress check questions are providedthroughout this book to help evaluate yourindividual learning needs. Answers to theprogress check questions with page referencesare provided to assist you in determining yourstrengths and weaknesses. If you have difficultyanswering certain questions, refer to the pagereference on the answer sheet and review thematerial until you feel confident that youunderstand the information.Take as much time as you need to master thematerial. You may not answer the questions 100percent correctly the first time around. Withstudy, you will quickly master those a reas youmay have difficulty with.As you read through the book you will notice thatsome words are bolded. Words found in boldtext are listed in the glossary at the end of thebook. If, during your reading, you should comeacross a word that you are unfamiliar with, orunsure about the way in which the word is usedin the text, please refer to the glossary forclarification.TECHNICIANS COURSE OBJECTIVESUpon completion of this course you will beable to:n Distinguish between the principles of heattransfer.n Describe fixed orifice tube air conditioningoperation.n Describe thermostatic expansion valve airconditioning operation.

Intro-2

I Explain the difference between R-12 andR-l 34a refrigerants.n Explain the purpose of refrigerant safety andcontrol devices.H Describe heating system operation.n Describe symptom-to-subsystem-to-component-to-cause diagnostic procedure.n Identify refrigeration subsystem diagnosticprocedures.n Identify refrigeration subsystem testing andservice procedures.n Define retrofitting.H Identify heating subsystem diagnosticprocedures.H Identify heating subsystem testing and serviceprocedures.CLIMATE CONTROL CURRICULUMThere are a total o f six courses in the climatecontrol curriculum. Each course found in theclimate control curriculum is of one of thefollowing types:H Self-Study - This course is a self-pacedprogram. The technician is responsible for thematerial on his or her own. The trainingmaterial consists of a reference book and anaccompanying videotape. The videotapeassists the learner in understanding theinformation in the reference book. Therefore,the videotape should not be used on its own.H Ford Multimedia Training (FMT) - Thiscourse is also self-paced. The multimediacourse allows the technician to interact withthe training materials. The multimedia courseallows the technician to apply the knowledgelearned in the self-study courses.n Instructor-Led - The instructor-led course

allows for practical, real world, application ofskills and knowledge learned in the self-studyand multimedia courses.

Introduction


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FORD CUSTOMER SERVICE DIVISION

STST CLIMATE CONTROLCURRICULUM PATH

LEGEND= PREREQWSlTE

SELF STUDY

Course CodesCurriculum Training Pathway

Climate Control SystemsThese courses may be located in the STARSplanner using the following codes:Refrigeration and Heating 35SOl SO.Air Management and Controls . 35SO2SO

Diagnosis . . . . 35S03MOAdvanced Climate ControlSystems Diagnosis . . . . ..*.... 35S04TO

lntmduction Intro-3


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The first two courses in the curriculum areprerequisites to the climate control courses.The first prerequisite course is the AutomotiveElectrical Systems course. The course may betaken by either multimedia or instructor-ledmethods. The second prerequisite course isAutomotive Electronics. The AutomotiveElectronics course can also be taken viamultimedia or instructor-led means.The third course in the curriculum isRefrigeration and Heating: Operation, Diagnosisand Service. This course is a self-study coursewith accompanying video (you are currentlyholding the student reference book). The fourthcourse in the climate control curriculum is Air

Management and Controls: Operation, Diagnosisand Service. The fourth course is also a self-study course with accompanying video. Coursefive, Climate Control Systems Diagnosis, is aninteractive multimedia course. The sixth and finalcourse is Advanced Climate Control SystemsDiagnosis. The sixth course is an instructor-ledcourse that will bring together all of theinformation learned in the first five courses andwill apply that information in a real world setting.One final point about the climate controlcurriculum; the information learned in eachcourse is closely related to the information foundin the course before it. Therefore, the coursesneed to be followed in the correct order.

Intro-4 Introduction


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PURPOSE OF CLIMATE CONTROLThe purpose of the climate control system is toprovide passenger comfort. The climate controlsystem must be able to provide this comfortunder a variety of environmental conditions:extreme heat, humidity and cold.A vehicles passenger compartment can absorbheat from the sun, engine, exhaust, pavement,and the passengers themselves. At other timesthe vehicles passenger compartment can giveup heat to outside sources, such as ice, snow,rain and wind. All of these sources transfer heatby radiation, conduction or convection. Whenthe heat is transferred it can create mild toextreme passenger discomfort.

Another source of passenger discomfort ishumidity. Humidity is the moisture content of air.We have all heard the old saying, its not theheat, its the humidity. The amount of humidity inthe air affects the rate of evaporization ofperspiration from the body. Dry air (lowhumiditv) causes raoid evaboration. whichmakes the skin feelcool. Maoist air (highhumidity) slows down the evaporation ofperspiration, which makes the skin feel hot.Therefore, as the amount of humidity goes up,so does the level of discomfort. This is why a70F (21 C) heat with 30% humidity feels hotterthan a 90F (32C) heat at 5% humidity. Theclimate control system provides passengercomfort by removing or adding heat and byremoving moisture from the air.

RAIN

Sources of Vehicle Heat

Introduction In trod


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LESSON I: PRINCIPLES OF HEAT TRANSFER

n Define sensible and latent heat.n Explain the principles of heat transfer.

n Types of Heatn The Six Heat Transfer PrinciplesW Principle Onen Principle TwoW Principle Threen Principle Fourn Principle Fiven Principle Sixn Progress Check One

Lesson 1


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TYPES OF HEATAtoms are in a constant state of motion. Heat isthe form of energy which causes an atom to bein motion. Temperature is the measurement ofan atoms movements. When the heat of anatom is increased, the movement of the atom(temperature) increases. W hen the heatdecreases, the atom slows down. If all the heatcould be removed from an atom (a temperatureof absolute zero), all motion would stop.Temperature alone does not give the amount ofheat in a substance. It only indicates the degreeof warmth. It is important not to use the wordsheat and temperature carelessly becausethey are not interchangeable.There are two basic types of heat. Sensible heatis the heat which causes matter to changetemperature. This type of heat is measurablewith a thermometer and it can be felt, thus thename sensible.

The amount of heat necessary to change thetemperature of a substance is determined by itsspecific heat capacity. Specific heat capacity ismeasured in British Thermal Unlts ([email protected] substance can hold a certain amount ofheat before the substance changes temperature.The amount of heat that is needed to change thetemperature of one pound of the substance onedegree Fahrenheit is called the specific heatcapacity.Different substances have different specific heatcapacities. For example, the specific heatcapacity of water is 1 O BTU/lb 1 OF. Therefore,if 1 .O BTU of specific heat is added to a pound ofwater, the pound of water will increase itstemperature 1 F (.556%). To expand on thiseven more, lets take a pound of water that iscurrently 32F (OC), which is its freezing point.If we add 180 BTUs of specific heat to thepound of water, the temperature will increase to212F (1 OOOC), he boiling point.

1 B.T.U

Specific Heat Capacity

Lesson I


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1 LB. OF LIQUIDWATER ~20F$EEZING 1 LB. OF LlQUlD WATERAT BOlLlNG POINT(2129ff

speclnc neat capacity of WaterMatter exists in one of three states: a solid,liquid or vapor. The state of any matter is water can be either a liquid or a vapor. The stateis determined by the amount of latent heat thedependent on the matters temperature, water contains.pressure and heat content. For matter to changestate from a solid to a liquid, the matter mustabsorb heat. Once a liquid, if the mattercontinues to absorb heat it will eventually changeto a vapor. The opposite of this is also true; if a-liquid releases heat it will become a solid.

SOLlD LlQUlD VAPOR

BLOCKOF ICE WATER ST&iii

-. -. ___Tnree States of MatterHeat which causes matter to change stateswithout a change in temperature is called latentheat. Latent heat is the second type of heat. Thistype of heat is also called hidden heat. Latentheat is also measured in BTUs, however, it doesnot affect temperature the way specific heatdoes. Latent heat is important for changes instate to occur. For example, waters liquid stateexists between the temperatures of 32F and212F (0C and 100C at sea level). Its vaporstate exists at temperatures of 212F (1 OOOC)and above. At the temperature of 212F (1 OOOC),

To illustrate the relationship between specificheat, temperature, and latent heat, please referto the chart. The chart is a temperature-heatdiagram for one pound of water at atmosphericpressure, heated from -460F (-274C) throughvaporization. At point A there is one pound of icethat is -460F (-274C). At point B there is onepound of ice at 32F (OOC). The differencebetween point A, -460F (-274C) and point B,32F (OOC) s 492F (274C). Since the specificheat content of ice is .5 BTUs/lb, it will take atotal of 246 BTUs of specific heat to raise thetemperature from point A to point B .At point B there is ice at 32F (OOC). At point Cthere is water (liquid) that is also 32F (OOC). Inorder to get from point B to point C (changestates from solid to liquid), latent heat must beadded. The latent heat of ice is 144 BTUs/per lb.Therefore, adding 144 BTUs o f latent heat to theice changes it to a liquid. Remember that thetemperature will remain at 32F (0C) during thechange of state.

Lesson 1

So, at point C there is water (liquid) at 32F(0C). At point D there is water (liquid) that is212F (100C). Once again, to get from point C,32F (0C) to point D, 212F (1 OOOC), specificheat must be added. The specific heat capacityof water is 1 O BTU/lb. Since the differencebetween point C and point D is 180F (1 OOC),180 BTUs of specific heat must be added to thewater to reach point D from point C.

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At point D there is water (liquid) at 212F(100%). At point E there is steam (vapor) that isalso 212F (100C). In order to get from point Dto point E (change states from liquid to vapor),latent heat must be added again. The latent heatof water is 970 BTUs/per lb. Therefore, 970BTUs of latent heat must be added to the water(liquid) before it will complete ly change states tosteam (vapor). Remember that the temperaturewill remain at 212F (100%) during the changeof state.

Once again, at point E there is steam at 212F(100%). At point F there is steam that is 300F(149%). So, to get from point E, 212F (100C)to point F 300F (149C), specific heat must beadded. The specific heat capacity of steam is.48 BTU/lb. S ince the difference between point Eand point F is 88F (49C), 42 BTUs of specificheat must be added to the steam to reachpoint F from point E.

ATMOSPHERIC PRESSURE (14.7 P.S.I.)Off E POUND WATER

-460

HEAT (BTUS)

I emperarure-near ulagram

Lesson


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It is also important to understand that after all thewater has turned to vapor by absorbing 970BTUs, the absorption of latent heat stops. At thispoint, the vapor will be 212F (100C) which isthe same temperature it was as a liquid.However, now that the water has vaporized,specific heat can once again be absorbed toraise the temperature. Since the specific heatcontent of steam (water vapor) is -048 BTU/lb.(which is about a half BTU per OF), then for every1 .O BTU the vapor absorbs of specific heat, thetemperature will raise about two degreesFahrenheit.This fundamental law applies to othersubstances as well, including the refrigerantsused in Ford Motor Company vehicles. However,the quantity of heat absorbed will vary,depending on the following three factors:1) the substance; 2) the state; and 3) the amountof latent heat needed to change states. The tworefrigerants used by Ford Motor Company areR-l 34a and R-l 2.

Lesson 1

PRINCIPLE THREEThe third law of heat transfer is that the mass ofany object will remain the same regardless of theheat content or state. For example: one pound ofwater will always be one pound of water, nomatter if its a solid, liquid or vapor. This principleis applied throughout the entire refrigerationsystem.

ONE POUND

ICE LIQUID STEAM

MASS REMAINS THE SAMEHeat Content and State Does Not Change Mass

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PRINCIPLE FOURThe fourth principle of heat transfer is latentheat of condensation. Changing states from avapor to a liquid, w ithout a change in

temperature, is latent heat of condensation. Thisprinciple occurs in the exact opposite manner aslatent heat of vaporization. Latent heat ofcondensation is applied in the condenser.

300

32

ATMOSPHERIC PRESSURE 114.7 P.S.I.)ONE POUND WATl%

1584 1540 - 970 = 570 390 246 0BTUS OF LATENT HEAT

HEAT (BTUS)

Latent Heat of Condensation

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PRINCIPLE FIVEThe evaporating temperature (boiling point) forany liquid is affected by the pressure placed onit. Increasing pressure increases the boilingpoint. Decreasing the pressure decreases theboiling point. The automotive cooling sys tem is agood example. The radiator cap keeps the waterin the engine from boiling by allowing the coolingsystem to build up pressure. A radiator capallows the boiling point to rise 3F (1.68%) for

each pound the radiator cap is rated at. Sincewater boils at 212F (100%) at sea level, a 16psi (110 kPa) radiator cap will allow the coolanttemperature to reach 260F (127%) beforeboiling. This way, increased pressure allows thewater to reach higher temperatures beforeboiling. In an automotive refrigeration system,Liquid refrigerant pressure is changed at thefixed orifice tube. Refer to the illustration to seehow temperature affects refrigerant pressure.

Pressure Changes Temperature

Pressure Changes Temperature

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PRINCIPLE SIX Therefore, since the condensation point hasThe sixth principle of heat transfer is that when avapor is compressed, its temperature andpressure will increase. For example, in a properlycharged system, if we compress R-i 2 vapor from30 psi to 180 psi (206 kPa to 1241 kPa) the

been increased, if heat is removed from thevapor, lowering the temperature below130F (54%) the vapor will condense into aliquid. In an automotive refrigeration systemvapor pressure is changed at the compressor.boiiing point/condensation point will increase.

LOW PRESSURECOOL VAPOR HIGH PRESSUREHOT VAPOR

TEMPERATURE INCREASES WITH PRESSURECompression Changes Temperature and Pressure

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PROGRESSCHECKONE1. Which of the following statements about humidity is true?

A. Low humidity allows rapid evaporation.B. High humidity makes the skin feel cooler.C. As humidity goes down, the level of discomfort goes up.D. Low humidity allows slow evaporation.

2. Which o f the following allows matte r to change states without a change in temperature?A. Specific heat capacityB. Sensible heatC. Latent heatD. British Thermal Units (BTUs)

3. When a hot object contacts a cooler object, heat will flow from .A. the larger object to the smaller objectB. the smaller object to the larger objectC. the hot object to the cold objectD. the cold object to the hot object

4. The temperature of a pound of liquid water is 212F (100%). What will happen when 970 BTUs oflatent heat are added?A. The temperature increases without changing state.B. The liquid changes to vapor and the temperature increases.C. The liquid changes to vapor and the temperature stays the same.D. The liquid changes to vapor while dropping temperature.

5. Whenever matter changes state from a vapor to a liquid, it will always .A. lose heatB. absorb heatC. increase in temperatureD. decrease in temperature.a

6.. Changing states from a vapor to a liquid, without a change in temperature is called:A. Latent heat of vaporizationB. Latent heat of liquificationC. Latent heat of condensationD. Latent heat of solidification

Check your answers by using the answer key in Appendix A, then start the video tape.

Lesson I I-1


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Ford Motor Company uses two types of airconditioning systems. The most common systemis the fixed orifice tube system. The fixed o rificetube system provides cooling for the majority of

Ford Motor Company cars and light trucks. Som eadvantages of the fixed orifice tube system are:I better reliabilityW less weight and production cost

OUTSIDE AIRTHROUGH CONDENSE

COLD DISCHARGE AIRlNT0 VEHICLE INTERIOR

m HIGH PRESSURE HIGH TEMPERATURE GAS-HIGH PRESSURE HIGH TEMPERATURE LIQUID=LOW PRESSURE LOW TEMPERATURE LIQUIDm LOW PRESSURE LOW TEMPERATURE GAS/LlQUIDa LOW PRESSURE LOW TEMPERATURE GAS

Fixed Orifice Tube System

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The other system is the thermostatic expansionvalve system. The thermostatic expansion valvesystem may be found on some com pact cars. Itis also common on vans to have a front fixedorifice tube system and a rear auxiliarythermostatic expansion valve system (usually nota complete system as it shares components with

the front fixed orifice tube system). Some of theadvantages of a thermostatic expansion valvesystem include:n more precise control of the air conditioningq less frequency of compressor clutchengagement

CONDENSER HfGH PRESSUREnlCPUnanc t 1?4E

OUTSIDE A1RTHROUGH CONDENSER A

EVAPORATOR/ CAPILLARY t --I

COLD DISCHARGE AIRINTO VEHICLE INTERIOR

LOW PRESSURELIQUtD LINE

HIGH PRESSURE HIGH TEMPERATURE GASHIGH PRESSURE HIGH TEMPERATURE LIQUZD

sjl LOW PRESSURE LOW TEMPERATURE LIQUIDLOW PRESSURE LOW TEMPERATURE GAS

Thermostatic Expansion Valve System

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COMPRESSORRCI tTCH

CONDEeER- ---.-..

\ HIGH PRESSUREDISCHARGE L[NE

@lTSlD!Z AIRTHROUGH CONDENSER

ACCUMULATOR/DRIEREVAPORATOR

LOW PRESSURESUCTlON LtNE/

HIGH PRESSURELIQUID LINERXED ORIFICE TUBE \\

COLD DISCHARGE AIRI INTO VEHlCLE INTERIOR

HIGH PRESSURE H IGH TEMPERATURE GAS=HIGH PRESSURE HIGH TEMPERATURE LiQUlD

LOW PRESSURE LOW TEMPERATURE LfQUtDLOW PRESSURE LOW TEMPERATURE GAS/LIQUID

lZ3LOW PRESSURE LOW TEMPERATURE GAS

Evaporator Removes Heat and Humidity

Lesson 2


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depending on the air flow requirements of a The fans allow the heat transfer to be efficient byparticular vehicle. Strategies for operating the circulating the air. The other components of theelectro-drive fan will be discussed in the Air system could not effectively apply the heatManagement and Controls course. transfer principles without the aid of the fans.

ENGINE DRIVEN

BLOWER MOTOR FAN

U HlGH PRESSURE HIGH TEMPERATURE GASi HlGH PRESSURE HIGH TEMPERATURE LlQUiDCl LOW PRESSURE LOW TEMPERATURE LKXJiDCZI LOW PRESSURE LOW TEMPERATURE GASILIQU1D0 LOW PRESSURE LOW TEMPERATURE GAS

Lesson 2

Fans Increase Heat Transfer Efficiency

2-11


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REFRIGERATION CYCLEThe compressor builds up refrigerant pressure inthe discharge side (high pressure side) againstthe restriction of the fixed orifice tube. Therefore,pressure is raised in the condenser (principle six)and lowered in the evaporator and suctionaccumulator/drier (principle five). Duringoperation, when the liquid refrigerant passesthrough the fixed orifice tube, refrigerantpressure and temperature drops. This meansthat the boiling point has also dropped and theliquid will evaporate at the reduced temperature.The refrigerant boiling point has been lowered bylowering the pressure in the evaporator. The fanblows hot passenger compartment air throughthe evaporator fins. Passenger compartment

lesson 2

heat is absorbed by the liquid refrigerant in theevaporator causing it to vaporize (principle two).During the intake (suction) stroke of thecompressor, the heated vapor is pulled from theevaporator, through the suction accumulator/drier, and into the compressor. The compressionstroke reduces the volume of the vapor.Compressing the vapor creates pressure andincreases the vapor temperature (principle six).This high pressure vapor enters the condenserand is hotter than the ambient air being b lownthrough the condenser. Therefore, heat transfersto the outside air (principle one) andcondensation takes place (principle four) as thevapor gives off its heat to the outside air andbecomes a liquid.

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THERMOSTATIC EXPANSION VALVESYSTEMThe thermostatic expansion valve system is usedon fewer vehicles than the fixed orifice tubesystem. The system uses the same operatingprinciples and refrigerant cycle as the fixedorifice tube system. The main differences arethat the expansion valve system uses:n a thermostatic expansion valve andn a receiver/drier

The rest of the components are the same asthose found on the fixed orifice tube system.They include the:n Evaporatorn Compressor and clutchn Condensern Fans

HIGH PRESSUREDtSCHARGE LINE

OUTSIDE AIRTHROUGH CONDENSE

SENSING BUL3EVAPORATOR

COLD D&CHARGE AIRINTO VEHICLE INTERIOR

HIGH PRESSURE HIGH TEMPERATURE GASHIGH PRESSURE HIGH TEMPERATURE LIQUIDLOW PRESSURE LOW TEMPERATURE LiQUIDLOW PRESSURE LOW TEMPERATURE GAS

Thermostatic Expansion Valve System

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Thermostatic Expansion ValveThe thermostatic expansion valve controlsrefrigerant flow using a ball and plate assemblythat is moved by pressure differentials. Thethermostatic expansion valve has an inletpassage from the condenser on one end and anoutlet passage to the evaporator on the otherend. In between the inlet and outlet passages isa ball and plate assembly.The ball and plate assembly has an expansionvalve spring connected to it on one side. On theother side of the ball and plate assembly are twopush pins that connect a diaphragm to the balland plate assembly. A sensing bulb and capillarytube allow the pressure at the diaphragm tochange. The pressure in the diaphragm worksagainst the pressure of the expansion valvespring to move the ball and plate assembly.When the pressure in the diaphragm overcomesthe expansion valve spring pressure the ball andplate assembly opens and allows greaterrefrigerant flow. When the expansion valvespring overcomes the pressure in the diaphragmthe ball and plate almost closes and stops themajority of refrigerant flow. For lubricationpurposes, some liquid refrigerant and oil must beallowed to reach the compressor.

Lesson 2 2-15

SENSING BULB\

CAPILLARY TUBE

EXPANSiONVALVE SPRING

TO EVAPORATOR

Thermostatic Expansion Valve ControlsRefrigerant to Evaporator


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PROGRESS CHECK TWOFor questions 1-4, choose the correct definition (A-F) for the components listed. Use each definitiononce, not all of the definitions will be used.

1. Accumulator/Drieruction2. - Evaporator3. Condenser4. - Fixed Orifice Tube

A. Uses principles one, three and four to liquify refrigerant.B. Uses principles one, two and three to vaporize refrigerant.C. Prevents excessive liquid from entering the compressor.D. Sto res excessive vapor leaving the condenser.E. Regulates refrigerant into the evaporator by sensing evaporator outlet temperature.F. Allows the high and low side pressure differentials to maximize evaporator and condenseroperation.

For questions 5-8, choose the correct location (A-D) in the simple A/C system shown below where youwould find the liquid or vapor described.5. - Low pressure liquid6. - High pressure vapor7. - High pressure liquid8. - Low pressure vapor

Check your answers by using the answer key in Appendix A, then resume watching the video tape.

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LESSON 3: REFRIGERANTS

H Explain the difference between R-12 andR-l 34a refrigerants.n Describe the Montreal Protocol andClean Air Act.n Explain the difference between YN-9 andYN-12 refrigerant oils.

Lesson 3

I Environmental Concernsn Effects of Chlorofluorocarbonsn The Montreal Protocol and Clean Air Actn Refrigerant Oils

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EFFECTS OF CHLOROFLUOROCARBONSThe earth is protected from harmful ultravioletradiation by the atmospheres stratosphericozone layer. Scientists believe that certain man-made chemicals called chlorofluorocarbons(CFCs) are destroying the stratospheric ozonelayer. This loss of ozone in the upperatmosphere could cause health andenvironmental concerns.

Refrigerants for automotive air conditioners areone of the single largest users of CFCs in theUnited States, making up about 20% of totalusage. Prior to legislation, CFCs were commonlyreleased into the air during service of A/Csystems. When CFCs reach the stratosphere,high energy u ltraviolet radiation breaks themolecules apart. This process releases chlorine,which attacks the ozone layer. A single chlorineatom can destroy over 10,000 ozone moleculesand stay in the atmosphere for over 120 years.

Simulated Ozone DepletionCAtlTiUN: Refer to the MaterElaI SafetyData Sheet for importanf informationpertaining to ktealth and safety cortcerns

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THE MONTREAL PROTOCOL ANDCLEAN AIR ACTIn 1987, the United States and 22 other countriessigned the Montreal Protocol, a treaty to limit theamount of CFCs produced worldwide. Sincethen, the number of countries agreeing to theprovisions of the treaty has increased.Under the Montreal Protocol, signing countriesagree to a uniform reduction of the production ofCFCs and to completely phase out production byJanuary 1, 1996.Provisions of the Montreal Protocol aresupported by the United States Environmental

Protection Agencys (EPA) Clean Air Act. The1990 Amendments to the Clean Air Act requirestandards for controlling ozone depletingsubstances that are more strict than thosecontained in the Montreal Protocol.A key element in the control of ozone depletingsubstances addressed by the Clean Air Act isrefrigerant recovery. Major domestic and foreignvehicle manufacturers have approved theservicing of mobile air conditioners under newvehicle warranty using recycled refrigerant.Recycling is expected to greatly reduce thedischarge of R-12 into the atmosphere andreduce the demand for pure, virgin, R-l 2.

ROTUNDA R-134aA/C SERVICE CENTER176-00001ROTUNDA R-l 2REFRIGERANT MANAGEMENTCENTER 176-00102

- -_ _- ^_ _.Refrigerant Recovery stations

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Some key requirements of the Clean Air Act are:n As of January 1, 1992, technicians who repairor service automotive air conditioning systemsmust be certified in refrigerant recovery and

recycling by an EPA approved certificationprogram and must properly use certifiedequipment when performing service. A copy oftheir certification must be maintained by theiremployer. Refer to state and local ordinancesconcerning the posting or displaying ofcertifications.n Any person or facility repairing or servicingR-l 2 automotive air conditioners mustproperly use refrigerant recovery equipmentthat has been approved by the EPA. Recoveryof R-134a will be required in November 1995.

Every facility that performs service of A/Csystems must prepare and submit a facilitycertification to the U.S. EPA to declare that itis properly using approved equipment and thateach individual using the equipment isproperly trained.n Recovery/recycling/recharging equipmentmust be certified by the EPA or an EPAapproved testing laboratory as of January 1,1993. Certification means that the equipmentalso meets requirements for operational safetyand effectiveness.n Effective November 15, 1992, it becameunlawful to sell or distribute, or offer for sale,R-l 2 automotive refrigerant in containers ofless than 20 pounds except to certifiedtechnicians servicing motor vehicle airconditioners.H Distributors must sign statements describingtheir requirements on the sale of smallcontainers of refrigerant.n Air conditioning service facilities are subject tocompliance checks by EPA representatives.Failure to comply may result in severe finesand penalties to both the technician and therepair facility.

Lesson 3

R-l 34a REFRIGERANT SYSTEMSThe most important thing to understand aboutR-l 34a and R-l 2 air conditioning systems is thatthey are not entirely the same. They havecomponents that are slightly different from oneanother and in some cases service requirementsare also different. R-l 34a refrigerant andcomponents can only be used on R-134asystems, while R-l 2 refrigerant and componentscan only be used on R-12 systems, unlessotherwise specified during a retrofit operation.Retrofitting is a procedure used to change anR-l 2 A/C system to an R-l 34a A/C system.Retrofitting will be discussed later in this course.It is important to determine which type of A/Csystem a vehicle has before servicing thesystem. The biggest key to identification of therefrigerant in a system is to check the vehiclesrefrigerant charge tag. The charge tag is locatedin the engine compartment and will clearly stateR-134a or R-12. Another clue that a system maybe an R-134a system is the gold NON-CFC tagsthat are found on some vehicles refrigerantlines. However, not all vehicles have the goldNON-CFC tags, so, be sure to check therefrigerant charge tag whenever possible.Additionally, always use the refrigerant identifierto determine the purify of the refrigerant in asystem (refer to refrigeration testing and servicefor information on the refrigerant identifier).

3-5


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PRESSURE 150(PSI)

100TEMP (F)

Refrigerant Temperature/Pressure Relationship ChartThere are several differences between theR-l 34a and R-l 2 systems that you need to beaware of. One difference is that the servicecharge ports have been changed so that R-12special service equipment cannot be connectedto an R-l 34a system and vice versa. R-l 34a

system service charge ports only accept thequick-connect couplings of R-l 34a serviceequipment. R-l 2 system service charge portsaccept the screw-on type couplings forschrader valves.

R-l 34a R-12

LOW SIDE HIGH SIDE

HIGH SIDE LOW SIDE

Service Charge Ports

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Another difference is that R-l 34a uses a differenttype of refrigerant oil than R-12. When replacingR-l 34a components always use YN-12 oil.YN-12 is not suitable for R-12 systems so do nottry to use it in an R-12 system. The lastdifference that you should be aware of is thatR-l 34a systems use an A/C pressure cut-offswitch. The A/C pressure cut-off switch is notused on the majority of R-12 systems. A/Cpressure cut-off switch operation is discussedlater in this course.

compressor ot -12 refrigerant oil

REFRIGERANT OILSFord Motor Company uses two types ofrefrigerant oils; one type each for R-l 2 andR-l 34a systems. All R-l 2 A/C systems use amineral based oil called YN-9. The R-134a A/Csystems currently use polyalkylene glycol (PAG)oils which are synthetic. Most Ford, Lincoln, andMercury vehicles use YN-12 oil. To determinethe type and amount of refrigerant oil that is inthe system refer to the refrigerant charge tag.PAG and mineral oils ARE NOT INTER-CHANG EABLE. Do not attempt to use YN-9refrigerant oil in an R-134a system. This isbecause mineral based oil will not mix with theR-l 34a and circulate through the system, it justseparates and sits on the bottom of theevaporator or suction accumulator/drier whichmeans the compressor is not being lubricated. Itis important to know that refrigerant oils absorbmoisture. Therefore, always keep the cap on thecontainer to keep moisture out whenever you arenot using the oil.

a CAUTION I A MIS EN GARDE

Check the Refrigerant Charge Tag to identify the OilCAUTION: Refer to the Material SafetyData Sheet for important informattonpertaining to heatth and safety ccncern$of refrigerant oils YN-9 (fox No, 034490)and Y N-l 2 (Tcx No. 123567).

3-8 Lesson


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THERMOSTATIC DE-ICING SWITCHThe thermostatic de-icing switch is similar to theA/C cycling pressure switch. Its purpose is tocontrol compressor clutch engagement onthermal expansion valve systems. Thethermostatic de-icing sw itch is connected inseries with the compressor clutch circuit and isconnected to a temperature sensor which isinserted in the evaporator core fins.As the temperature of the evaporator decreases,the temperature sensor resistance increases,causing the electrical contacts to open anddisengage the compressor clutch. Since thecompressor is not turning, the low side pressuresand temperature increase. As the temperature ofthe evaporator increases, the temperaturesensor resistance decreases, causing theelectrical contact to close and engage thecompressor clutch.

A/C PRESSURE CUT-OFF SWITCHLocated on the high side o f the A/C system,there are two types o f A/C pressure cut-offswitches: a single function and a dual functionswitch. The single function switch is used tointerrupt compressor operation in the event ofhigh discharge pressures by opening the cyclingpressure switch circuit.The dual function switch is usually found onvehicles that have two speed electro-drive fans.When discharge pressures are high, the dualfunction switch will engage the high speedcooling fan first. This will attempt to lowerdischarge pressures by increasing heat transferefficiency at the condenser. However, if thedischarge pressure continues to rise after the fanhas been engaged, then the switch will interruptcompressor operation just like the single functionswitch.

TEMPERATURESENSORc/

Thermostatic De-king Switch

SINGLE FUNCTION DUAL FUNCTIONA/C PRESSURE CUT-OFF SWITCHES

Contain Refrigerant by LoweringSystem PressuresA/C PRESSURE TRANSDUCERThe A/C pressure transducer providesinformation to the variable control relay module(VCRM). The VCRM then uses the pressuresignal from the transducer to control the fanoperation and A/C clutch circuit. VCRM operationis described in Air Management and Controls -Operation, Diagnosis and Service.

Lesson 4 4-3


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HIGH PRESSURE RELIEF VALVEThe high pressure relief valve is usually found inthe compressors high pressure dischargemanifold or on the discharge line. This reliefvalve prevents damage to the A/C systemcomponents by relieving high side refrigerantpressures in excess of 450 psi (3103 kPa). Thehigh pressure relief valve closes to prevent totalrefrigerant loss after relieving excessivepressures.

HIGH SIDEI PRESSURE RELIEF VALVE I

Relieves Excessive High Side Pressures

LOW PRESSURE RELIEF VALVEThe low pressure relief valve relieves pressuresin excess of 250 psi (1724 kPa) that may buildup due to high ambient air temperatures. Thevalve is found on the low side o f the system.Refer to the service manual for the specificlocation of the vehicle being serviced.

LOW SIDEPRESSURE RELIEF VALVE

Relieves Excessive Low Side Pressures

Lesson 4


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PROGRESS CHECK THREE1. As of the 1994 model year, all Ford, Lincoln, and Mercury vehicles utilize R-l 34a A/C systems.Why was this necessary?

A. Because R-12 is believed to be harmful for the environment.B. Because R-12 is a CFC.C. Because R-l 34a is the only approved replacement refrigerant.D. All of the above answers are correct.

2. Which of the following is a key requirement of the Clean Air Act which is important for everyclimate control technician to know?A. Technicians who service A/C systems must be certified in refrigerant recovery and recycling.B. Employers must maintain a copy of each technicians certification.C. All recovery, recycling and recharging equipment must be certified by the EPA.D. All of the above answers are correct.

3. Which of the following is used to control evaporator temperature and prevent evaporator icing?A. A/C pressure cut-off switchB. A/C cycling pressure switchC. Low pressure relief valveD. High pressure relief valve

4. Where is the A/C cycling pressure switch located and what circuit does it cycle?A. Near the condenser, the control head ground circuitB. Near the compressor discharge, the compressor clutch circuitC. Near the suction accumulator/drier, the compressor clutch circuitD. Near the evaporator inlet, the refrigerant containment switch circuit

5. W hich device is found on many retrofit vehicles and is used in case of extreme ambient airtemperatures?A. High pressure relief valveB. Thermostatic de-icing switchC. A/C pressure cut-off switchD. Low pressure relief valve

Check your answers by using the answer key in Appendix A, then resume watching the video.

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LESSON 5: HEATING SYSTEM OPERATION

n Describe heating system operation. H Heater Hosesn Heater CoreH Blower Motor (Fan)n Water Valve (Some Vehicles)n Heating Cyclen Progress Check Four

Lesson 5 5-l


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BLOWER MOTOR [FAN]The blower motor is the same one used in the airconditioning system. The blower motor circulatesthe passenger compartment air through theheater core so that heat transfer may take place.The blower motor does not directly apply any ofthe heat transfer principles. However, the heatercore could not effectively apply the heat transferprinciples without the aid of the blower motor.Blower motor control will be covered in the AirManagement and Controls self study.

HEATER BiOWER FANBlower Motor Fan Increases Heat TransferEfficiency

WATER VALVE (SOME VEHICLES)Ford Motor Company uses a water valve to shutoff the engine coolant flow to the heater core onsome vehicles. The reason for this is to improveair conditioning efficiency by keeping hot coolantout of the heater core during A/C operation. Thewater valve can also be found on the auxiliaryheating system of some vans. Water valvecontrol will be covered in the Air Managementand Controls self study.

HEATER COREWATER VALVE

/

Water Valve in the Heater Core Inlet

Water Valve in the Heater Hose Line

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HEATING CYCLENow that the basic heating system componentshave been identified, lets see how they operatetogether as part of the engine cooling system.You should a lready be familiar with basic enginecooling system operation, so the followingexplanation will assume that you understand howthe basic engine cooling system componentsoperate.Starting at the engine water jackets, heat fromthe engine is transferred (principle one) to thecoolant. As the hot coolant circulates through theengine, a portion of the hot coolant flows througha heater hose to the heater core. The blowermotor circulates the cold passengercompartment air over the heater core fins. Heatis transferred (principle one) from the hot coolantto the heater core fins and to the circulated air.The coolant then flows out the heater core,through a heater hose and back to the engine

Lesson 5

water jackets. W ith the thermostat open, thecoolant flows out of the water jacke ts, throughthe thermostat, and to the radiator inlet by way ofa radiator hose.As hot engine coolant enters the radiator inlet,the cooling fan pulls cooler outside air throughthe radiator which allows heat transfer (principleone) from the radiator to the outside air. Thecoolant then flows out the radiator outlet, througha radiator hose, and into the water pump. Thewater pump circulates the coolant back to thewater jackets.When the engine is first started, the coolant isnot warm enough to open the thermostat. Withthe thermostat closed, coolant flows through abypass back to the water pump so that thecoolant can be sent to the water jackets again.The coolant will continue to bypass thethermostat until the coolant temperature gets hotenough to open the thermostat.

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PROGRESS CHECK FOUR1. When diagnosing heating concerns, which engine cooling system components could be at fault?

A. Water pumpB. RadiatorC. ThermostatD. Any of the above answers

2. At which component is heat transferred from hot engine coolant to the passenger compartmentair?A. ThermostatB. Heater coreC. Blower motorD. Radiator

3. What is the purpose of the water valve on some Ford vehicles?A. To maintain a constant supply of hot engine coolant to the heater core.B. To shut off any engine coolant flow to the heater core during A/C operation.C. To divert engine coolant flow to the heater hoses when the heat is ON.D. To divert engine coolant that is returning from the heater core to the water pump.

Check your answers by using the answer key in Appendix A, then resume watching the video.

5-6 Lesson 5


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DIAGNOSTIC PROCEDURE to identify the system or subsystems that may beThe flowchart that follows has been created toprovide a logical diagnostic procedure. When acustomer brings a vehicle in for service, he orshe has a concern. The first step of theprocedure is used to collect information aboutthe vehicle and the symptoms related to thecustomers concern. Step 2 allows the technician

causing the customers concern. Step 3 is usedto isolate the specific components of a systemand identify the root cause so that the correctrepair can be made. Finally, steps 4 and 5 allowthe technician to perform the service action andverify that the correct repair was made. Lets lookat each of these steps in detail.

DIAGN0STICPR0CEDURE

Includes:- Review RO- Identify Conditions UnderWhich Concern Occurs- Check OASIS- Check TSBs- Check Service History- Relate Customer Concernto Technical Symptom- Perform Operational Check

Includes:- Identify possible sub-systems via prechecks

Includes:- Interpret test results- Isolate root cause ofconcern

Includes:- Test vehicle for initialcustomer concern- Note any new symptoms

6-4Diagnostic Procedure

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Air ManagementControls

Low engine coolant levelWrong degree thermostatPlugged heater coreClosed water valveSee Air Management and Controls -Operation, Diagnosis and ServiceSee Air Management and Controls -Operation, Diagnosis and Service

Wind noise Air ManagementHigh speed only on blower motor Controls

See Air Management and Controls -Operation, Diaonosis and Service ISee Air Management and Controls -Operation, Diagnosis and Service

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2. PrechecksOnce we have established the symptom and theconditions of the symptom, we must look at thesubsystems that may cause the initial concern.The overall system that we are diagnosing is theclimate control system. However, that really doesnot help us much, so we must break the climatecontrol system into subsystems.There are a couple of things to consider whenidentifying the possible subsystems. First of all,select the subsystems that are most likely tocause the symptoms. For example, our vehicle isnot cooling in heavy traf fic with stop and gotraffic. Therefore, the order of likely subsystemswould be as follows:n The refrigeration system is the most likely

subsystem due to a low refrigerant charge orpoor airflow through the condenser area.n The heating and engine cooling system is thesecond most likely due to an overheatingengine causing excessive heat in the radiatorwhich a ffects the condenser efficiency. Again,this is because of poor air flow through theradiator/condenser area or low coolant level.n The control and air management systems arean unlikely cause o f the concern. The reasonfor this is that the vehicle does not cool inheavy stop-and-go traffic, but we know that

the vehicle cools sufficiently at cruising speedsbecause we test drove the vehicle. Mostcontrol and air management problems wouldcause the no cooling condition at both cruiseand idle. However, the control and airmanagement systems should not becompletely ruled out until the prechecks and/ortesting verify that they are not the cause of theconcern. Which takes us to our secondconsideration.

The next issue is to isolate the possiblesubsystems. The subsystems can be isolated byusing the information gathered in the operationalcheck and by performing subsystem prechecks.The self-test would also be performed at thispoint if the vehicle was an automatic or electronicclimate control system. However, for this coursewe will only address manual climate controlsystem concerns and leave automatic andelectronic concerns for the next self studycourse; Air Management and Controls -Operation, Diagnosis and Service.Prechecks allow you to rule out the unlikelysubsystems while verifying the most likelysubsystems. Prechecks are basically mini-teststhat can be done quickly, without complicatedprocedures, and usually without tes t equipment.Most prechecks are the yes/no type of tests andare not specification tests. The order in whichyou perform prechecks will vary depending onthe prioritized list of subsystems. You shouldperform the prechecks in the same order as theyappear on the prioritized list. Referring back toour sample problem, since the refrigerationsubsystem is the most likely cause, we will startwith the refrigeration prechecks first and performthe air management prechecks last. One lastcomment on prechecks: Sometimes you neednot perform all of the prechecks. Lets face it, ifyou open the hood and see that the compressorhas physically blown apart, you are not going tospend your valuable time checking therefrigerant line temperatures.

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The following list of prechecks can be done onmost any climate control system:n Check for compressor clutch operation. Is itcycling? If not, the control subsystem may bepreventing engagement.n Check for any air flow obstructions in front ofthe condenser/radiator area. Remove anyobstructions, such as bent front fascias orroad debris.q Check the refrigerant line temperatures. Thecomponents and lines that are under highpressure should be warm. The low pressurecomponents and lines should be cold.w Examine the refrigerant lines for frost ringsthat may indicate an obstruction in the line(frost rings are normal at the fixed orifice tubeor thermostatic expansion valve).H Check all of the electrical connections. Arethey plugged in and intact? Make sure youcheck the compressor clutch connector andthe electric fan connectors.n Check for loose, missing, or damaged drivebelts.q Check the engine coolant level.I Examine the heater/radiator hoses. Are theyleaking? Are all ,the hoses warm? If not there

may be an obstruction in the heater core or astuck thermostat in the engine cooling system.H Look for any obvious physical damage. Arethere any gaping holes in the system? Linesbroken? Engine coolant spraying in the enginecompartment?

Lesson 6

3. Diagnostic TestsPerforming tests on a subsystem will identifywhether the subsystem being tested is the causeof the symptom. You should always refer to theservice manual for the tests and testingequipment that should be used on the vehicle.The service manual will guide you to performsystem specific tests based on the results of theoperational check and prechecks that you havealready performed. Refer to the symptom chart inthe service manual.Symptom ChartThe symptom chart will help you find the causeof a malfunction. The chart uses the symptom-to-subsystem-to-component-to-cause diagnosticmethod by listing the conditions of operation, thepossible causes of the concern, and the action(test) to perform. For example, on the vehicle weare diagnosing we have collected the followinginformation:H The customer concern is no cooling.n The symptom and condition is no cooling instop and go traffic.n We suspect the refrigeration subsystem to becausing the concern.1 During the prechecks the discharge air could

have been colder and even though thecompressor clutch was cycling, it seemed tocycle very fast.

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Looking at the symptom chart we find A/CClutch Cycles Rapidly under the CONDITIONcolumn of the chart. Reading to the right, thePOSSIBLE SOURCE states Refrigerant. Stillreading to the right we read Go to Pinpoint TestKl under the ACTION column. This leads us tothe refrigerant systems tests where we canisolate the cause of the concern. (Refer to the

Refrigeration System Diagnosis Section of thisself-study for more information.)

CLIMATE CONTROL SYSTEMCONDITION I POSSIBLE SOURCE I ACTION II 1 1) 0 Heat Always On l Temperature blend cable. 1 GO to Pinpoint Test A 1. 11 Temperature control lever. I I

l Insufficient Heat0 Ventilation system.

1 Water thermostat. 1 GOtoPinpointTestBi.0 Coolant level.l Heater water hoses.l Heater core.

l Insufficient A/C Cooling 0 Insufficient refrigerant.l Refrigerant leak(s). l GO to Pinpoint Test C l.

l No Operation In All Temperature l Temperature control door. l GO to Pinpoint Test Dl.Settings l Loose or broken temperaturecontrol door cable.l Damaged temperature controllever system.l Ducts broken or leakina.

l A/C Blower Motor Does Not 0 Fuse(s). 0 GO to Pinpoint Test El.Operate 0 Circuit.l A/C blower motor.0 A/C blower motor resistor.0 Blower motor switch.

l A/C Blower Motor Runs Constantly 0 Circuit.l Blower motor switch.

l A/C Blower Motor Does Not 0 Circuit.0 GO to Pinpoint Test F 1.l GO to Pinpoint Test G 1.Operate Properly l Blower motor switch.0 A/C blower motor resistor. I I

l No Operation in Low Blower 0 Circuit. l GO to Pinpoint Test Hl.Setting l A/C blower motor resistor.0 Blower motor switch. Il No Operation in High Blower 0 Circuit. l GO to Pinpoint Test J 1.Setting 0 A/C blower motor resistor.

l Blower motor switch.l A/C Clutch Cycles Rapidly l Refrigerant. 0 GO to Pinpoint Test Kl,

l A/C pressure cut-off switch.l A/C cycling switch.

0 A/C Clutch Does Not Engage 0 Fuse. l GO to Pinpoint Test Ll.

6-10sample symptom tinart

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K2s

nwmm


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DISCHARGE AIR TEMPERATURE TESTThe Discharge Air Temperature Test is aneffective test to help in determining whether ornot the refrigeration system is operating properly.The test is based on a graph which plots thecenter vent discharge air temperature againstoutside ambient temperatures of 60-l 00F(16-38%). The NORMAL area of the graphshows the allowable, discharge air temperaturesat a given ambient temperature. The rangeprovided in the NORMAL area is necessary tocompensate for humidity.You will need to refer to the service manual forthe vehicle and system that you are diagnosing.In general, if the discharge air temperature iswithin specification for the ambient temperaturemeasured at the time the vehicle is tested, therefrigeration system is functioning properly. If thedischarge air temperature is out of specification,more testing is required.

C10.8.0.4.2.O-

NORMAL CENTER AfC REGISTERDISCHARGE TEMPERATURES

! ! ! ! ! ! ! t ! ! ! ! !.? I

I 15 20 2s 30 33 cAMBIENT TEMPERATURES

u Air Discharge Temperature Graph

Lesson 7

One thing that you will notice when looking at thegraph is that the discharge air temperatureincreases as ambient air temperature increases.This is important for you to understand becauseyou may need to explain the discharge air/ambient air temperature relationship to acustomer that feels his vehicle should be coolerinside. For example, Mr. Jones decides to travelacross the good-ole US of A in his trusty Fordvehicle. He starts his trip in mid-July fromnorthern Minnesota where the ambienttemperature is 70F (21 C) and the discharge airtemperature is 35F (2C). After a few weeks, hedrives into a dealership in southern Floridawhere the ambient temperature is lOOoF (38%)with 70% humidity and complains that his vehicledoes not cool because the discharge airtemperature is only 50F (9C). Little does Mr.Jones know that he should be happy to have anin-vehicle temperature of 50F (9%) when its100F (38%) ambient. The only thing thecustomer sees is an increase in temperature of15F (7C) in the vehicle. You will need toexplain to him that the 30F (17C) increase inambient temperature and humidity affects theperformance of the climate control.

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COMPRESSOR CLUTCH CYCLE TIMEIf the Discharge Air Temperature Test was out ofspecifications, and you suspect the refrigerationsubsystem to be at fault, then the compressorclutch cycle time and rate should be checked.The clutch cycle time and rate can only bechecked on fixed orifice tube systems and isdone in conjunction with the refrigerant linepressure checks. Clutch cycle time and ratetesting is based on graphs which providespecifications for clutch on time, off time, totalclutch cycle time, and clutch cycle rate.

The clutch on time is the length of time inseconds that the clutch is engaged.The clutch off time is the length of time inseconds that the clutch is disengaged.Total clutch cycle time is on time added to offtime or, in other words: the amount of time thatthe clutch is engaged, plus the amount of timethat it is disengaged.The clutch cycling rate is the number of totalclutch cycles in one minute.

+PLUS = EQUALSTOTALCTrMCELNG

CLUTCH ON CLUTCH OFFENGAGED TIME DISENGAGED TIME

Determining Compressor Clutcn cycle i-ime

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Lets look at an example. You are observing acompressor clutch. You see the clutch engageand you start a timer. The clutch then dis-engages after 12 seconds (the on time). Youkeep the timer running. The clutch is disengagedfor 8 seconds (the off time) before re-engaging.As soon as the compressor re-engages, you stopthe timer. Since we had 12 seconds of on timeand 8 seconds of off time, the timer must havestopped at 20 seconds (12 on + 8 off =20 seconds). Therefore, the total clutch cycling

time is 20 seconds. This cycle from clutchengagement, through disengagement, untilre-engagement is 1 cycle. If the total clutch cycletime continues to be 20 seconds, the cycling ratefor one minute is 3 (20 sets. x 3 = 60 sets.).Sometimes the compressor clutch will notdisengage when operating in extremely highambient air conditions. When this happens theclutch cycle time and rate is stated ascontinuous run.

PL+uS= EQUALSTOTALCYCLINGTIME OF20 SECONDS

CLUTCH ON CLUTCH OFFTIME IS 12 SECONDS TIME IS 8 SECONDS

Total Clutch Cycle Time

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REFRIGERANT LINE PRESSURETESTINGRefrigerant line pressure testing is based oncomparing actual system pressures to normalpressures for the ambient conditions in which thesystem is tested. The graphs that are providedindicate a normal pressure range for both highand low sides of the system. The rangescompensate for humidity.Refrigerant line pressure testing can be used foraccurate diagnosis on fixed orifice tube andthermostatic expansion valve systems when theclutch is running continuously or when clutchcycle times appear normal but the discharge airtemperature is low.In order to perform accurate pressure testing, itis necessary to properly connect a manifoldgauge set to the high and low pressure sides ofthe air conditioning system and measure therefrigerant pressures while the system isoperating.

LOW-PRESSUREGAUGE ANDSERVICE HOSEHlGH PRESSUREGAUGE AND

CENTER SERVlCE HOSEROTUNDA R-134a MANIFOLDGAUGE SET 176-R032A

Manifold Gauge Set

Lesson 7

Manifold Gauge SetThe manifold gauge set is one of the mostimportant refrigeration diagnostic tools that youwill use. Every manifold gauge set should havethe following components:W Low pressure gaugeq Low pressure hand valven Low pressure service hose (blue)n High pressure gaugen High pressure hand valven High pressure service hose (red)W Center service hose (yellow)Low Pressure Side [Blue]The low pressure side of the manifold gauge setincludes the gauge, hand valve, and servicehose. The service hose is required to have ashut-off valve or Schrader valve no more than12 from the end. This is to reduce the amount ofrefrigerant that is released to the atmospherewhen the hose is disconnected from the A/Csystem. The type of coupling found on the end ofthe hose depends on the type of refrigerantsystem that the manifold gauge set is designedfor. If the gauge set is to be used with an R-134asystem it will have quick-connect couplings. If thegauge set is to be used with an R-12 system itcan have either screw-on or quick connectcouplings for the threaded shrader valveservice port.The pressure gauge measures vacuum in inchesof mercury (in.-Hg) and pressure in pounds persquare inch (psi). The control valve for the lowpressure side is a hand valve located below thecompound gauge. It is used to open or closethe low pressure service hose to the centerservice hose during the recovery and rechargingprocess (covered later in this course). The lowpressure gauge is always monitoring the low sideservice hose pressure, regardless of the handvalve position.

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High Pressure Side [Red]The high pressure side of the manifold gauge setalso includes a gauge, hand valve, and servicehose. As with the low pressure service hose, thehigh pressure service hose must also have ashut-off valve or Shrader valve located within 12from the end to reduce the amount of refrigerantthat is released to the atmosphere.The high pressure gauge reads pressure onlyand is calibrated in pounds per square inch (psi).The control valve for the high pressure side is ahand valve located below the pressure gauge. Itis used to open or close the high pressureservice hose to the center service hose. The highpressure gauge is always monitoring the highside service hose pressure, regardless of thehand valve position.Center Service Hose [Yellow]The center service hose is attached to the centerport of the manifold gauge set and is used duringthe recovery, evacuation, and rechargingprocesses. The center service hose must alsohave a shut-off valve or Shrader valve at thehose end to reduce the amount of refrigerantreleased to the atmosphere and to seal off thegauge set when disconnected from a vacuumpump, charging cylinder, or recovery station.

7-8

AdaptersSince 1981, factory installed R-l 2 systems havea 3/8 (95mm) high pressure service charge portThese charge ports require an adapter toconnect the high pressure manifold gauge sethose to the vehicle service charge port. RotundaHigh Side Adapter Set 081 L-l 9703-A shouldcontain all of the necessary adapters.

Rotunda High Side Adapter Set D81 L-19703

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Connecting the Manifold Gauge Set to anR-l 34a SystemThe procedure for connecting the manifoldgauge set to an R-134a system is similar to theR-l 2 system. However, follow this procedure.

1. Wear safety goggles. Do not wear safetyglasses.2. Remove the protector caps from the servicecharge ports.3. Make sure that the manifold gauge set handvalves are closed (turned clockwise, and allthe way in).4. Turn the valve depressor knob on top of thequick connect fitting all the way to the left(counter clockwise) . This will prevent the

quick connect fitting valve depressor fromopening the service charge port internalvalve and provide the necessary clearanceneeded for connection.5. Pull the cage of the quick connect fittingupward while installing the fitting onto theservice charge port. Make sure the cage ofthe quick connect fitting snaps downward,locking the fitting into place.6. Turn the valve depressor knob on top of thequick connect fitting to the right (clockwise).This will cause the valve depressor to open

the service charge port internal valve,allowing refrigerant pressure into the gaugeset hose.CAUTION: Wear safety goggles andglaves. Keep the service hoses directedAWAY from your face when connectingand disconnecting the service hoses.Make sure that the service hoses arerouted AWAY from the drive belts andengine Goofing fan.

7-10

Interpreting Pressure ReadingsOnce the manifold gauge set has beenconnected and conditional testing requirementshave been met, you should get some reliablepressure readings on the gauges. Refer to theappropriate graph in the service manual for thenormal pressure readings for the vehicle you aretesting. Determine whether the pressures arehigh, normal, low, or erratic.

IIaII11111:IIIII

,

NORMAL AK: EVAPORATOR COREORIFICE CYCLING BK: CLUTCHm Pal REFRIGERANT SYSTEM PRESSURES

16&IENT TE2:PERAlUR&

22 C

Normal High and Low Side Operating PressuresRefer to the Refrigerant System Pressure andA/C Clutch Cycle Timing Evaluation Chart that ifound in the service manual. Read the left twocolumns of the chart to locate the appropriatepressures. Match the pressure results in the lefttwo columns with the clutch cycle times and ratein the center three columns. Once you have thepressures, rate, and clutch cycle times matchedup, read the Component-Cause in the far rightcolumn. Pet- form any additional tests or individualcomponent testing as directed by the servicemanual.

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PRESSURE TESTING THERMOSTATICEXPANSION VALVE SYSTEMSIn general, thermosta tic expansion valve systempressures will be lower (at the same ambienttemperature) than those of fixed orifice tubesystem s. The clutch will also cycle lessfrequently than a fixed orifice tube clutch cyclingsystem.There are no clutch cycling times or rates tocheck on the thermostatic expansion valvesystem. The diagnosis relies on systempressures only. The pressure test should beconducted in conjunction with the discharge airtemperature test. Both the pressure test anddischarge air test are performed just as the fixedorifice tube system. The only difference will bethe specifications. Specifications for a typicalthermostatic expansion valve system areprovided below. Additional tests can be made onthe thermostatic expansion valve and de-icingswitch. Please refer to the service manual forindividual component testing.

pa w NORMAL REFRIGERANT SYSTEM PRESSURESOW.=276-,250

lb nb ail&IENT TEMPERATURESG .,

LEAK TESTINGAny time a vehicle enters the dealership with alow refrigerant charge or no refrigerant charge,you should test the system for leaks. Manyrefrigerant leaks can be found by a simple visualinspection. However, if a visual inspection doesnot reveal the source of a refrigerant leak, youwill need to test the system with an electronicleak detector or with tracer dye.Preparing the SystemIn order to perform the leak test, the system mustbe under pressure. If the suction line (line fromthe evaporator to the compressor, including thesuction/accumulator drier) is cold with the systemoperating there is usually enough refrigerant inthe system to leak test.If the refrigerant line pressure readings are zero(empty) or near zero, an external source ofrefrigerant will be required. For testing,refrigerant pressure may be supplied by arefrigerant charge station. It is not necessary tocompletely charge a system for leak testing,charge the system to a minimum of 50 psi.However, prior to charging, visually inspect thesystem for obvious leaks such as broken hosesor spring lock couplings.

Normal High and Low Side Operating Pressures

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The general procedure for using tracer dyes todetect leaks is as follows:1. Add the tracer dye to the A/C systemfollowing the dye manufacturersinstructions.2. Run the A/C system fo r 5-10 minutes tocirculate the dye.3. Shine an ultraviolet lamp on the refrigerationsystem to look for traces of dye, indicatingleaks.

Large leaks will show up

Documents

21990813 Automotive Heating Cooloing Systems