Heater and Air Conditioner, Blend Air System ...ww2.justanswer.com/uploads/budnshe/2010-04-15_023718_file.pdf · 15.04.2010 · NOTE: The actuator has no feedback to the FCU/ACU to

A/C Performance DiagnosisProblem—Warm Airflow When the Air Conditioner is On, A/C Not Working, or Poor A/C Performance (dash outlettemperature is too high)

Problem—Warm Airflow When the Air Conditioner is On, A/C Not Working, or Poor A/C Performance (dash outlettemperature is too high)

Possible Cause Remedy

Refrigerant charge too low. Perform leak test. Repair any leaks, evacuate the system, replace thereceiver-drier (only if color indicates it is saturated with moisture), add a fullcharge of refrigerant.

Contaminated refrigerant. Check refrigerant for moisture and/or mixed refrigerant contamination, repairas necessary.

Refrigerant charge too high. Evacuate the system, charge system with proper amount of refrigerant.

Moisture in the system. Moisture in the system may cause ice crystals to form and possibly block theflow of refrigerant at the expansion valve or other places in the system.Recover the refrigerant, replace the receiver-drier, evacuate the system, andadd a full charge of refrigerant.

A/C compressor not working. The refrigerant charge is too high or too low (will cause the binary pressureswitch to open and prevent the compressor from operating).

Worn or loose A/C compressor drive belt, tighten or replace as necessary.

Faulty A/C compressor or clutch, repair as necessary.

A/C compressor clutch not engaging. See "A/C Clutch Circuit" for diagnosis.

Ice formed on evaporator core. Ice buildup on the evaporator core can block airflow through the evaporator,thus producing little or no cooling. This may occur if the compressor is notcycling off at the correct temperature. For evaporator sensor testing, see"Evaporator Temperature Sensor."

Temperature door not operating correctly,front and auxiliary units.

Electrical problem with temperature actuator. Check for fault codes.

See fault code tables, in Subject 340 , for diagnosis.

Mechanical problem with temperature door. Check for obstructions or brokencomponents, repair as necessary.

NOTE: The actuator has no feedback to the FCU/ACU to verify position. Ifthere are no fault codes and the actuator signal appears to be working in theDataLink Monitor template, then suspect a mechanical problem.

Wiring problem between climate controlpanel and ACU, auxiliary unit only.

See Table 11 , Sleeper Climate Control Panel Circuit Diagnosis.

Faulty temperature control potentiometer. See Table 11 , Sleeper Climate Control Panel Circuit Diagnosis.

Blockage or restriction in refrigerantsystem.

A blockage or restriction can usually be found by locating an abrupttemperature change at a location in the system; for example, in a line or thecondenser. Repair as necessary.

Blower motor in protection mode (reducedairflow).

See "Blower Motor."

System out of calibration, front unit only. See "Calibration Procedure."

Heater and Air Conditioner, Blend Air System,Troubleshooting 83.06

Symptom Driven Diagnosis

Columbia Workshop Manual, Supplement 21, June 2010 350/1

Problem—No Fresh Air, Front Unit Only (nonrecirculation mode)

Problem—No Fresh Air, Front Unit Only (nonrecirculation mode)


Recirc door not operating correctly. Electrical problem with recirc door actuator. Check for fault codes.


Also see "Recirculation" and "Actuator Stepper Motors—Temperature, Recirc,and Mode."

Mechanical problem with recirc door. Check for obstructions or brokencomponents, repair as necessary.


Restricted filter or intake. Clean as necessary.

System out of calibration. See "Calibration Procedure."

Problem—Low Side Pressure Too Low

Problem—Low Side Pressure Too Low


Refrigerant system restriction or blockage. Check the expansion valve and other components for blockage (blockage maybe due to moisture causing ice buildup).

Refrigerant charge too low. Perform leak test. Repair any leaks, evacuate the system, replace thereceiver-drier (only if color indicates it is saturated with moisture), add a fullcharge of refrigerant.

Problem—High Side Pressure Too High

Problem—High Side Pressure Too High


Restricted airflow through condenser. Check for dirt and debris buildup in front of condenser, clean as necessary.

Check engine fan operation.

Restriction or blockage in condenser orline from condenser to receiver-drier.

Restriction or blockage will usually be indicated by a cool spot or ice buildupnear the restriction or blockage. Repair as necessary.

NOTE: If the compressor has recently failed, the restriction may be due toleftover debris from the failed compressor.

Air in refrigerant. Check refrigerant purity, evacuate, and charge as necessary.

Engine overheating. Check engine cooling system.

Engine fan not working correctly. See Group 20 , check fan cycling switch.

Heater and Air Conditioner, Blend Air System,Troubleshooting83.06


Columbia Workshop Manual, Supplement 21, June 2010350/2

Problem—Compressor Runs Continuously

Problem—Compressor Runs Continuously *


Refrigerant charge too high. Evacuate the system, replace the receiver-drier (only if color indicates it issaturated with moisture), add a full charge of refrigerant.

Faulty evaporator temperature sensor. See "Evaporator Temperature Sensor."* This is normal when the ambient temperature and/or relative humidity is high.

Problem—Little or No Heat, Front and Auxiliary Units

Problem—Little or No Heat, Front and Auxiliary Units


Low engine coolant. Check coolant level.

Plugged heater core. Flush coolant system or replace heater core as necessary.

NOTE: This can be checked by feeling the inlet and outlet heater hoses.There should be a slight temperature difference when the temperature is setto hot and the fan is on high (engine at operating temperature). A largetemperature difference indicates a blockage.

Faulty engine thermostat. Check if thermostat is stuck open, this may cause the engine to not reachoperating temperature under light load or when ambient temperatures are low.

Temperature door not operating correctly. Electrical problem with temperature actuator. Check for fault codes.


Also see "Override."




Problem—Water or Engine Coolant Leaking from HVAC Unit Inside the Cab, Front and Auxiliary Units

Problem—Water or Engine Coolant Leaking from HVAC Unit Inside the Cab, Front and Auxiliary Units *


Plugged drain tubes. Clean as necessary.

Leaking heater core. Replace heater core.* Clear water dripping from the HVAC unit under the hood is normal when the A/C is on. This is from moisture condensing out of the air as it cools going

through the evaporator.




Problem—Recirculation Mode Not Working, Front Unit Only

Problem—Recirculation Mode Not Working, Front Unit Only


Recirc door not operating correctly. Electrical problem with recirc actuator. Check for fault codes.


Also see "Recirculation" and "Actuator Stepper Motors—Temperature, Recircand Mode."

Mechanical problem with recirculation door. Check for obstructions or brokencomponents, repair as necessary.


System out of calibration. See "Calibration Procedure."

Problem—Air Does Not Come Out of Correct Outlets, Front Unit Only

Problem—Air Does Not Come Out of Correct Outlets, Front Unit Only *


Mode door not operating correctly. Electrical problem with mode actuator. Check for fault codes.


Also see "Recirculation" and "Actuator Stepper Motors—Temperature, Recircand Mode."

Mechanical problem with mode door. Check for obstructions or brokencomponents, repair as necessary.


Broken or disconnected duct. Repair as necessary.

System out of calibration. See "Calibration Procedure."* For example, air directed to windshield outlets when air selection switch is set to floor outlets.

Problem—Warm Air from Outlets When Temperature is Set to Cold (A/C not on)



Temperature door not operating correctly. Electrical problem with temperature actuator. Check for fault codes.


Also see "Actuator Stepper Motors—Temperature, Recirc, and Mode."









Wiring/temperature control problem,auxiliary unit only.


Problem—No Backlighting, Front Unit Only

Problem—No Backlighting, Front Unit Only


Dim signal not reaching the FCU or faultyFCU.

See "Backlighting Diagnosis."

Problem—Blower Not Working, Operates at Reduced Speed, or Runs Then Shuts Off, Front and Auxiliary Units

Problem—Blower Not Working, Operates at Reduced Speed, or Runs Then Shuts Off, Front and Auxiliary Units


Blower in protection mode. Check for fault codes.


If there are no active fault codes, refer to "Blower Motor" for more information.

Wiring problem.

Faulty blower motor.

Wiring problem between sleeper climatecontrol panel and ACU, auxiliary unit only.


Faulty blower control potentiometer,auxiliary unit only.


Problem—Bunk Override Does Not Work, SleeperCab Only (cannot override auxiliary blower and temperature settingsfrom the front)

Problem—Bunk Override Does Not Work, SleeperCab Only (cannot override auxiliary blower and temperaturesettings from the front)


Faulty bunk override switch. Check switch. See "Override" for diagnosis. Verify switch operation usingDataLink Monitor template.

Wiring problem. Check wiring between override switch and FCU.

No J1587 databus communicationbetween FCU and ACU.

Using ServiceLink, make sure both the FCU (MID 146) and ACU (MID 200)appear in the ECU list. If one ECU does not appear in the list, troubleshootthe J1587 databus. See Group 54 for more information. Also see "Override"for diagnosis.

NOTE: Vehicles without a sleeper do not have an ACU.

Faulty FCU. See "Override" for diagnosis.

Faulty ACU. See "Override" for diagnosis.




Problem—Rear Override Does Not Work, SleeperCab Only (minimum A/C support)

Problem—Rear Override Does Not Work, SleeperCab Only (minimum A/C support) *


Front not providing A/C support forauxiliary (rear override not working).

Check rear override function. See "Override" for diagnosis. Problem may beno J1587 databus communication between the ACU and FCU.

* Rear cannot override to request A/C compressor when front unit is off. This should also cause front unit to operate at minimum blower speed if off.

A/C Clutch Circuit DiagnosisBefore performing tests on the A/C clutch circuit, per-form the diagnostic tests in Table 1 .

NOTE: Do not perform the test procedures inTable 3 before performing the test procedures inTable 1 .

A/C Clutch Does Not Engage

TestNo. Test Test Procedure Test Result Action

1 Check controlsettings.

In order for the A/C compressorto operate, the controls must beset as follows:

• blower speed at any set-ting other than off

• air selection in one of A/Cor defrost settings

• A/C button is pressed;light on

• engine running above 450rpm

• ambient temperature atthe evaporator sensormust be above 44°F (7°C)forA/C compressor to en-gage

If these conditions are met, theA/C compressor should engage.It may cycle on/off.

Conditions met, A/Ccompressor engages.

No problem found.

Conditions met, A/Ccompressor does notengage.

Go to test no. 2 .

2 Check for fault codes. Connect ServiceLink and checkfor fault codes. Check if one ofthe following fault codes is ac-tive:

• 146 s011 05

• 146 s011 06

NOTE: See Front Control Unit(FCU) (MID 146) J1587 FaultCodes by SID table, inSubject 340 , for fault codedescriptions.

One of these faults isactive.

See Table 3 .

Faults other than theseare active.

Repair fault before proceeding.

No active faults. Go to test no. 3 .






3 Check if A/C requestis being sent.

Connect PC to vehicle and openthe Behr CDTC Blend Air HVACSystem DataLink Monitortemplate. Do the following:

• Start the engine.

• Set the blower to anyspeed except off.

• Set the air selectionswitch to face mode.

• Press the A/C button; thelight should be on.

Observe the A/C request annun-ciator in the template. The A/Crequest signal should be activeand the A/C compressor shouldengage when the previous condi-tions are met and the followingconditions are met:

• Evaporator sensor isabove 44°F (7°C).

• Engine speed above 450rpm. See template.

• Low air pressure signal isnot being broadcast bythe instrument cluster. Seetemplate.

A/C request signal is-active.

See Table 4 .

A/C request signal isnot active.

Go to test no. 4 .

4 Check evaporatorsensor.

Note the ambient air tempera-ture. Measure the resistance ofthe evaporator temperature sen-sor and compare the readingwith the value in Table 2 orFig.1 . The reading should corre-spond to a temperature approxi-mately equal to the ambient tem-perature.

NOTE: The evaporator sensortemperature must be above 44°F(7°C) before the FCU will sendthe A/C request signal to the A/Cclutch relay. Therefore thesensor resistance must be belowapproximately 6500 ohms. SeeTable 2 or Fig. 1 . Also seeFig. 2 .

Less than 6500 ohms Check wiring between FCU andevaporator temperature sensor. Ifokay and all other inputs aremet, such that the A/C requestsignal should be sent, thenreplace the FCU.Go to test no.5.

More than 6500ohms The FCU is not sending an A/Crequest signal because thesensor is indicating thetemperature is below 44°F (7°C).If temperature is known to bewell above this temperature, thenreplace the sensor. Go to testno. 5 .






5 Verify repair. Verify that repair resolved theproblem.

Problem resolved Done

Problem unresolved Repeat test no. 1 .

Table 1, A/C Clutch Does Not Engage

Evaporator Temperature Sensor Temperature versus Resistance

Temperature °F(°C)

Resistance (ohms) Temperature °F(°C)

Resistance (ohms)

20 (–6.7) 12,814 55 (12.8) 4792

25 (–3.9) 11,036 60 (15.6) 4209

30 (–1.1) 9535 65 (18.3) 3706

32 (0) 9000 70 (21.1) 3271

35 (1.7) 8265 75 (23.9) 2894

40 (4.4) 7183 80 (26.7) 2566

45 (7.2) 6259 85 (29.4) 2281

50 (10) 5468

Table 2, Evaporator Temperature Sensor Temperature versus TemperatureResistance

A/C Request Circuit Test


1 Which fault code isactive? NOTE: Circuit problems between

the FCU and A/C clutch relay(coil side) will activate faultcodes.

146 s011 05 is active Go to test no. 2 .

146 s011 06 is active Go to test no. 5 .

2 Check A/C clutchrelay.

Remove the A/C clutch relayfrom the PDM.

Measure the resistance acrossthe relay coil (pins 85 and 86).

NOTE: If the relay coil is open,the resistance will beapproximately 680 ohms.

72–87 ohms Go to test no. 3 .

Not 72–87 ohms Replace relay.Go to test no. 7 .

3 Check A/C clutchrelay coil ground.

With the A/C clutch relayremoved, check resistancebetween the ground side of therelay coil (PDM side) and thenegative battery terminal.

Make sure the batteries aredisconnected or result may beinconclusive.

Less than 1 ohm Go to test no. 4 .

More than 1 ohm Repair relay coil ground circuit.Go to test no. 7 .




A/C Request Circuit Test


4 Check circuit 97T. Remove the A/C clutch relay.

Disconnect the B connector fromthe back of the FCU.

Measure resistance between thepower side of the relay coil (PDMside) and pin B10 at the FCU Bconnector.

Less than 1 ohm No problem found.Repeat testnumbers 1 through 4 .

More than 1 ohm Locate and repair highresistance or open in circuit 97T.Go to test no. 7 .

5 Check A/C clutchrelay.


Measure the resistance acrossthe relay coil (pins 85 and 86).

NOTE: If the relay coil is open,the resistance will beapproximately 680 ohms.

72–87 ohms Go to test no. 6 .

Not 72–87 ohms Replace relay.Go to test no. 7 .

6 Check circuit 97T forshort to ground.

Disconnect the B connector fromthe back of the FCU.

Measure resistance between pinB10 of the FCU B connector andthe negative battery terminal.

Make sure batteries aredisconnected or result may beinconclusive.

72–87 ohms No problem found. Repeat testsand look for possible intermittentshort to ground in circuit 97T. Goto test no. 7 .

Less than 72 ohms Locate short to ground in circuit97T. Repair as necessary. Go totest no. 7 .

7 Verify repair. Verify that repair corrected thefault code and the problem isresolved.

Problem resolved Done.


Table 3, A/C Request Circuit Test

NOTE: Do not perform the test procedures in Table 4 before performing the test procedures inTable 1 .

f040618

18000 16000 14000 12000 10000

6000 4000 2000

0 0°F 20°F 40°F 60°F 80°F 100°F

Temperature

Res

ista

nce

(Ohm

s)

8000

(−18°C) (−7°C) (4°C) (16°C) (27°C) (38°C)

Evaporator Sensor Temperature/Resistance

06/21/2002

Fig. 1, Evaporator Sensor Temperature/Resistance




A/C Clutch Circuit Test


1 Check power to A/Cclutch relay.


Turn the ignition on and checkfor voltage on the PDM socketthat corresponds to pin 87 A/Cclutch relay.

No voltage Go to test no. 2 .

12V Go to test no. 3 .

2 Check A/C clutchfuse.

Check the 20A A/C clutch fuse inthe PDM (fuse 55).

Fuse okay Check to make sure power isgetting to fuse. If okay, checkcircuit between fuse and A/Cclutch relay. Repair asnecessary, then go to test no.6.

Fuse blown Locate source of high currentbetween the PDM and the A/Ccompressor clutch. The circuitmay be shorted to ground.Repair as necessary, then go totest no. 6 .

3 Check A/C clutchcircuit resistance.

Remove the A/C clutch relayfrom the PDM. Measure theresistance between the PDMsocket that corresponds to circuit97T and the negative batteryterminal.

NOTE: Make sure batteries aredisconnected. Failure to do somay give inconclusive results.

2.85 to 4 ohms Check the A/C clutch relay. Makesure pin 87 is making contactwith pin 30 when the relay isenergized. Replace asnecessary, then go to test no.6.

More than 4 ohms Go to test no. 4 .

4 Check binary switch. Disconnect the binary switch andcheck continuity across theswitch terminals.

Continuity Go to test no. 5 .

No continuity Check refrigerant pressures. Ifpressure is below the binaryswitch cutout pressure, thesystem is severelyundercharged. Locate source ofleak and recharge.

If pressures are within the binaryswitch range, replace the binaryswitch then go to test no. 6 .




A/C Clutch Circuit Test


5 Measure resistanceof the A/C clutch.

Disconnect the connector at theA/C compressor. Measureresistance on the compressorside of the connector.

2.85–3.33 ohms Problem is most likely highresistance or open circuit inwiring between the A/C clutchrelay in the PDM and the A/Ccompressor. Be sure to checkA/C compressor clutch groundcircuit. The most definitive wayto isolate the problem is tomanually energize the circuit atthe relay and use voltage dropmeasurements to isolate theproblem, then go to test no. 6 .

Not 2.85–3.33 ohms Replace A/C compressor clutch,then go to test no. 6 .


Problem resolved Done.


Table 4, A/C Clutch Circuit Test

Bunk Override DiagnosisThe front control unit will remember bunk overridesetting after an ignition cycle and initiate bunk over-

ride again. Both the front and auxiliary units will be inbunk override mode.

See Table 5 for bunk override diagnosis procedures.

Bunk Override Diagnosis


1 Check bunk overridefunction with DataLinkMonitor Test.

Open the DataLink Monitortemplate for this system.

Turn the ignition on.

Set the front blower to high andthe temperature to hot.

Set the auxiliary blower to offand the temperature to cold.

In the template, press the bunkoverride ON test button.

The ACU bunk override modeannunciator state should be ONand the auxiliary blower andtemperature settings shouldmatch the front settings (can beobserved on the template. Notethat it takes about a minute forthe settings to completelychange.)

The ACU bunk overridemode state is ON andauxiliary blower andtemperature settingsclosely match frontsettings.

Go to test no. 3 .

The ACU bunk overridemode state is ON andauxiliary blower and/ortemperature settings donot match the frontunit.

Replace ACU, then go to testno. 5 .

The ACU bunk overridemode state is OFF orNA/ERR.

Go to test no. 2 .




Bunk Override Diagnosis


2 Verify J1587communication.

Connect ServiceLink to thevehicle. Check if both the FCU(MID 146) and ACU (MID 200)appear in the ECU list.

Both ECUs appear inthe ECU list.

Go to test no. 3 .

One or both ECUs donot appear in the ECUlist or ServiceLink isunable to connect tovehicle.

Troubleshoot and repair J1587databus. Refer to Group 54 formore information. Go to test no.5.

3 Check override switchoperation.


While observing the bunkoverride switch annunciator inDLM, press the switch to themomentary on position, then tothe momentary off position.

The annunciator should indicateswitch position. When the switchis in the normal position, theannunciator should indicate NA/ERR.

Switch functions asdescribed.

Go to test no. 4

Switch does notfunction as described.

Check override switch andwiring. Repair as necessary. Ifokay, replace the FCU. Go totest no. 5 .

4 Check if FCU issending bunkoverride request.


While observing the Bunk O/RRequest annunciator, press thebunk override switch to themomentary on position thenrelease it. The O/R requestannunciator should be in the ONstate then read NA/ERR.

Bunk O/R requestannunciator brieflyindicates ON then goesto NA/ERR and FCUand ACU bunk overridemode state is ON.

Problem not found. Verifycomplaint, check for intermittentproblems, repeat tests ifnecessary.

Bunk O/R requestannunciator remains inthe ON state.

Check ACU; it is not respondingto the bunk override request.Make sure it has power andground andJ1587 databuscommunication. If okay, replaceACU.

Go to test no. 5 .

Bunk O/R requestannunciator does notever indicate it is in theON state.

Repeat test 3. If okay, replaceFCU, then go to test no. 5 .


Problem resolved. Done.

Problem unresolved. Repeat test no. 1 .

Table 5, Bunk Override Diagnosis

See Table 6 for rear override diagnosis procedures.




Rear Override Diagnosis


1 Check rear overridefunction with DataLinkMonitor Test.

NOTE: If the frontunit diagnoses a badblower motor, then itwill not go into rearoverride mode andwill not activate theA/C request signal.



Set the front blower to off.

Set the auxiliary blower to highand the temperature to full cold.

In the template, press the rearoverride ON test button.

On the template, the FCU rearoverride mode annunciator stateshould be ON and the A/C modeannunciator should be ON. TheA/C clutch annunciator will notbe on unless the A/C requestrules are met (engine running, airpressure up, etc.).

The front blower should be onlow speed and the A/C indicatorlight on the A/C button should beon.

FCU rear overridemode state annunciatorin ON and A/C modeannunciator is ON.

Go to test no. 3 .

FCU rear overridemode state annunciatoris ON and A/C modeannunciator is OFF.

Replace FCU, then go to testno. 4 .

FCU rear overridemode state annunciatoris OFF.

Go to test no. 2

2 Verify J1587communication.

Connect ServiceLink to thevehicle.

Check if both the FCU (MID 146)and ACU (MID 200) appear inthe ECU list.

Both ECUs appear inthe ECU list.

Replace FCU, then go to testno. 4 .

One or both ECUs donot appear in the ECUlist or ServiceLink isunable to connect tovehicle.

Troubleshoot and repair J1587databus. Refer to Group 54 formore information. Go to test no.4.




Rear Override Diagnosis


3 Check if ACU issending rear overriderequest.


Start the engine.

Turn the front blower off.

While observing the RearOverride O/R Requestannunciator in DataLink monitor,set the auxiliary temperaturecontrol switch to full cold and theauxiliary blower speed to high.

The O/R Request annunciatorshould momentarily be in the ONstate, then read NA/ERR. It maytake a moment for this tohappen.

O/R Requestannunciator brieflyindicates ON , thengoes to NA/ERR, andFCU and ACU rearoverride mode stateannunciators are ON,and A/C mode stateannunciator is ON.

Problem not found. Rearoverride is functioning normally.

O/R Requestannunciator stays inthe ON state.

Check FCU. It is not respondingto the rear override request.Make sure it has power andground andJ1587 databuscommunication. If okay, replaceFCU. Go to test no. 4 .

O/R Requestannunciator does notever indicate it is in theON state.

Repeat test no. 3. If ambienttemperature is low, the auxiliaryunit may not request rearoverride. Replace ACU ifrepeated test fails. Go to testno. 4




Table 6, Rear Override Diagnosis

Actuator DiagnosisSee Table 7 for the actuator circuit test procedures.

Actuator Circuit Test


1 Check for fault codes. Check if any one of the followingfault codes is active:

f04061907/02/2002

146 s005 05146 s006 05146 s009 05200 s009 05

Group A Group B

146 s005 06146 s006 06146 s009 06200 s009 06

Single fault in Group Aisactive.

Go to test no. 2 .

All three MID 146 faultsare active in Group A.

Go to test no. 6 .

Single fault in Group Bis active.

Go to test no. 8 .

No faults listed inGroup A or B areactive.

No problem found.






2 Check voltage to theactuator.

NOTE: In order tomeasure a validvoltage, it may benecessary to movethe respective control:for recirc, press therecirc button; for mixdoor actuator, movethe temperaturecontrol switch; for themode actuator, movethe air selectionswitch.

For code 146s005 05 (front unit)disconnect the recirc actuatorconnector, turn the ignition on,measure voltage betweenconnector pin 1 and ground.

For code 146 s006 05 (front unit)disconnect the mode actuatorconnector, turn the ignition on,measure voltage betweenconnector pin 1 and ground.

For code 146 s009 05 (front unit)disconnect the temperatureactuator connector, turn theignition on, measure voltagebetween connector pin 1 andground.

For code 200 s006 05 (auxiliaryunit) disconnect the temperatureactuator connector, turn theignition on, measure voltagebetween connector pin 1 andground.

NOTE: See Fig. 2 , Fig. 3 , andFig. 4 .

Approximately 12V Go to test no. 3 .

Much less than 12V. Check wire between pin 1 of theactuator and the FCU/ACU foropen circuit. If okay, replaceFCU/ACU. Go to test no. 9 .






3 Check for short toground on return sideof actuator.

For code 146s005 05 (front unit)disconnect all three actuatorconnectors and the FCUconnector. At the recirc actuatorconnector, check continuitybetween connector pin 3 andground. Repeat for pins 4, 5, and6.

For code 146 s006 05 (front unit)disconnect all three actuatorconnectors and the FCUconnector. At the mode actuatorconnector, check continuitybetween connector pin 3 andground. Repeat for pins 4, 5, and6.

For code 146 s009 05 (front unit)disconnect all three actuatorconnectors and the FCUconnector. At the temperatureactuator connector, checkcontinuity between connector pin3 and ground. Repeat for pins 4,5, and 6.

For code 200 s009 05 (auxiliaryunit) disconnect the temperatureactuator connector and the ACUconnector. At the temperatureactuator connector, checkcontinuity between connector pin3 and ground. Repeat for pins 4,5, and 6.


Continuity to ground onany pin.

Locate short to ground, repair asnecessary, then go to test no.9.

No continuity to groundon any pin.

Go to test no. 4 .






4 Check continuity ofactuator return side.

For code 146s005 05 disconnectthe recirc actuator connector.

For code 146 s006 05disconnect the mode actuatorconnector.

For code 146 s009 05disconnect the temperatureactuator connector.

Check continuity between thefollowing connector pins:

A2B1B2B3

FCU

3456

Actuator

f04062007/02/2002

For code 200 s009 05 (auxiliaryunit) disconnect the auxiliary unittemperature actuator connectorand the ACU connector.

Check continuity between thefollowing connector pins:

B8B7B6B5

ACU

3456

Actuator

f04062107/02/2002


Continuity on all pincombinations.

Go to test no. 5 .

No continuity on one ormore pin combinations.

Locate open circuit, repair asnecessary, then go to test no.9.






5 Check actuator. For code 146s005 05 (front unit)perform "Actuator Stepper MotorElectrical Test" on the recircactuator.

For code 146 s006 05 (front unit)perform "Actuator Stepper MotorElectrical Test" on the modeactuator.

For code 146 s009 05 (front unit)perform "Actuator Stepper MotorElectrical Test" on thetemperature actuator.

For code 200 s009 05 (auxiliaryunit) perform "Actuator StepperMotor Electrical Test" on thetemperature actuator (auxiliaryunit).

Actuator okay. Replace FCU/ACU, thengo totest no. 9 .

Actuator not okay. Replace actuator, thengo to testno. 9 .

6 Check actuator returncircuits for open.

For all three active codes at thesame time, 146 s005 05, 146s006 05, 146 s009 05,disconnect all three actuatorconnectors and the FCUconnector. At each actuatorconnector, check continuitybetween the following connectorpins:

A2B1B2B3

FCU

3456

Actuator

f04062007/02/2002


Continuity on all pincombinations.

Go to test no. 7 .

No continuity on one ormore pin combinations.

Locate open circuit, repair asnecessary, then go to test no.9.

7 Check actuator returncircuits for short toground.

Disconnect all three actuatorconnectors and the FCUconnector. At the FCU connector,check continuity between pin A2and ground. Repeat for pins B1,B2, and B3.


Continuity to ground onany pin.

Repair short to ground, thengoto test no. 9 .

No continuity to groundon any pin.

Replace FCU, thengo to testno. 9 .






8 Check for shortedactuator coil.

For code 146s005 06 disconnectthe recirc actuator connector,check if fault no longer active(different fault maybe active).

For code 146 s006 06disconnect the mode actuatorconnector, check if fault nolonger active (different fault maybe active).

For code 146 s009 06disconnect the temperatureactuator connector, check if faultno longer active (different faultmay be active).

For code 200 s009 06disconnect the temperatureactuator connector (auxiliaryunit), check if fault no longeractive (different fault may beactive). See Fig. 2 .

Fault no longer active(FMI06), different faultmay be active (FMI05).

Shorted actuator motor is likely.Perform "Actuator Stepper MotorElectrical Test" to confirm, thengo to test no. 9 .

Fault still active(FMI06).

Check for short to ground inpower wire between actuator andFCU/ACU. If no short is found,replace FCU/ACU, then go totest no. 9 .

9 Verify repair.

NOTE: In order tocheck if a fault statushas changed fromactive to inactive, therecirc button,temperature controlswitch, or airselection switchneeds to be movedwhile the ignition ison.

Verify that repair resolved theproblem.



Table 7, Actuator Circuit Test

Temperature Sensor DiagnosisSee Table 8 for the evaporator temperature sensorcircuit test procedures.




Evaporator Temperature Sensor Circuit Test


1 Are evaporatortemperature sensorfault codes active?

Check if fault code146 s002 03or 146 s002 04 is active.

Neither fault isactive. Go to test no. 2 .

146s002 03 is active Check for sensor signal wireshorted to power. If okay, go totest no. 2 .

146s002 04 is active. Check for sensor signal wireshorted to ground. If okay,replace FCU. Go to test no. 3 .

2 Check sensorreference voltage.

Disconnect the evaporatorsensor.

Turn the ignition on and measurethe voltage across the sensorconnector pins (harness side).

The voltage should be 5V if thecircuit and FCU are operatingcorrectly.

5V Perform "EvaporatorTemperature Sensor Test."

Less than 5V. Check for open circuit in sensorsignal and ground wires. If okay,replace FCU. Go to test no. 3 .


Problem solved. Done.


Table 8, Evaporator Temperature Sensor Circuit Test

See Table 9 for the CDTC temperature sensor circuittest procedures.

CDTC Temperature Sensor Circuit Test


1 Are CDTCtemperature sensorfault codes active?

Check if one of the following faultcodes is active: 146 s001 03,146 s001 04, or200 s001 03,200 s001 04.

None of these faultsisactive.

Go to test no. 2 .

146s001 03 or 200s001 03 is active.

Check for sensor signal wireshorted to power. If okay, go totest no. 2 .

146s001 04 or 200s001 04 is active.

Check for sensor signal wireshorted to ground. If okay,replace FCU/ACU. Go to testno. 3 .

2 Check sensorreference voltage.

Disconnect the CDTC sensor.

Turn the ignition on and measurethe voltage across the sensorconnector pins (harness side).

The voltage should be 5V if thecircuit and FCU/ACU areoperating correctly.

5V Perform "CDTC TemperatureSensor Test."

Less than 5V. Check for open circuit in sensorsignal and ground wires. If okay,replace FCU/ACU. Go to testno. 3 .




CDTC Temperature Sensor Circuit Test





Table 9, CDTC Temperature Sensor Circuit Test

Backlighting DiagnosisSee Table 10 for backlighting diagnosis.

Backlighting Diagnosis


1 Check backlightingoperation.

Turn on the headlights andcheck for the followingconditions:

• Condition 1—all backlight-ing (instrument cluster,panel switches, and HVACFCU) not working

• Condition 2—HVAC FCUand bunk override switchbacklighting not working

• Condition 3—only HVACFCU backlighting notworking

• Condition 4—only bunkoverride switch backlight-ing not working

Condition 1 See Group 54 for backlightingdiagnosis.

Condition 2 Go to test no. 2 .



2 Check circuits 29Aand GND1.

Disconnect AS2 connector.

Turn headlights on.

Measure voltage at pins A(+) andF(–) of the AS2 connector on themain cab harness side.

9–16V Check AS2 connector for dam-aged pins. If damaged pins arefound, repair as necessary thengo to test no. 5 . If no damage isfound, repeat test no. 1 .

Less than 9V (0V) Check for open in circuits 29Aand GND1 in the main cab har-ness. Repair as necessary, thengo to test no. 5 .

3 Check circuits DIM+and GND1 to FCU.

Disconnect the FCU connector.

Turn headlights on.

Measure voltage at pins A6(+)and A7(–) of the FCU connector.

9–16V Replace FCU, then go to testno. 5 .

Less than 9V (0V) Check circuits DIM+ and GND1between the FCU connector andthe AS2 connector for circuit fault(open or short). Repair as neces-sary, then go to test no. 5 .




Backlighting Diagnosis


4 Check circuits DIM+and GND1 to overrideswitch.

Disconnect the override switchconnector.

Turn headlights on.

Measure voltage at pins 10(+)and 8(–) of the override switchconnector.

9–16V Replace the override switch,then go to test no. 5 .

Less than 9V (0V) Check circuits DIM+ and GND1between the override switch andAS2 connectors for circuit faults(open or short). Repair asnecessary, then go to test no.5.

5 Verify repair. Verify that repair solved thebacklighting problem.



Table 10, Backlighting Diagnosis

Sleeper Climate Control PanelCircuit DiagnosisSee Table 11 for sleeper climate control panel circuitdiagnosis.

Sleeper Climate Control Panel Circuit Diagnosis


1 Does the symptominvolve both theblower andtemperature control?

—

No, affects only one ofthese

Go to test no. 4 .

Yes, affects both Go to test no. 2 .

2 Check the 12VDCignition supply to thecontrol panel.

Gain access to the back of thesleeper control panel.

Disconnect the blower andtemperature potentiometerconnectors.


At the blower speedpotentiometer connector, checkfor voltage at pin A (circuit 98N).Repeat test for temperaturepotentiometer connector pin A(circuit 98N).

Voltage at both pins Go to test no. 3 .

Voltage at only one pin Check circuit 98N betweenconnector with no voltage andsplice in harness. Repair asnecessary.

No voltage at either pin Check 10A fuse in B-pillar PDM.If blown, check for short in circuit98N. If okay, check circuit 98Nfor open and check ignitionsupply to fuse panel. Repair asnecessary.




Sleeper Climate Control Panel Circuit Diagnosis


3 Check control panelground circuit.

Make sure the ignition is off andthe batteries are disconnected.Failure to do this may giveinconclusive test results.

Disconnect the blower andtemperature potentiometerconnectors.

At the blower speedpotentiometer connector, checkresistance between pin C (circuitGND) and the battery negativeterminal. Repeat test fortemperature potentiometerconnector pin C (circuit GND).

Both less than oneohm

Check ACU power and groundwiring. ACU may bemalfunctioning.

One more than 1 ohm Check GND circuit betweenaffected potentiometer circuit andthe splice in the harness. Repairas necessary.

Both more than 1 ohm Check GND wiring topotentiometers. Check ACUground circuit.

4 Which potentiometercircuit is affected?

Blower control Go to test no. 5 .

Temperature control Go to test no. 6 .

5 Check for blowerpotentiometer voltagesignal at the ACU.

Remove the ACU from the HVACunit; leave the connector pluggedin.


Backprobe ACU connector pinA2 and check for voltage whilerotating the blower speed controlknob from low to high.

Voltage ranges from0.5 to 12.5VDC

Sleeper climate control panelcircuit is not the problem. Checkfor fault codes and see "BlowerMotor Diagnostics–Front andAuxiliary Units."

Voltage does not vary;remains steadyregardless of value

Check circuit 98M betweenblower speed potentiometer andACU. Repair as necessary. Ifokay, replace potentiometer.

6 Check fortemperaturepotentiometer voltagesignal at the ACU.

Remove the ACU from the HVACunit; leave the connector pluggedin.


Backprobe ACU connector pinA5 and check for voltage whilerotating the temperature controlknob from cold to hot.

Voltage ranges from0.5 to 12.5 VDC

Sleeper climate control panelcircuit is not the problem. Checkfor fault codes and see "ActuatorStepper Motors—Temperature,Recirc, and Mode" fortemperature actuatordiagnostics.

Voltage does not vary;remains steadyregardless of value

Check circuit 98T betweentemperature potentiometer andACU. Repair as necessary. Ifokay, replace potentiometer.

Table 11, Sleeper Climate Control Panel Circuit Diagnosis

Blower Motor Diagnostics—Front and Auxiliary UnitsSee Table 12 and Table 13 for blower motor diag-nostics.




Blower Will Not Operate or Operates at Reduced Speed


1 Is fault 146 s010 02or 200 s010 02active?

—Yes See fault code tables, in

Subject 340 , for diagnosis.

No Go to test no. 2 .

2 Check power andground.

Disconnect the blower motorconnector.

Turn ignition on.

Check for voltage across pins 3and 4 of the connector.

NOTE: If system voltage is toohigh or too low, this may causethe blower motor to enter voltageprotection mode. This will causethe blower to operate at reducedspeed or stop working altogether.

12–17V (should beapprox. battery voltage)

Go to test no. 3 .

0V Check 30A blower motor fuse inPDM.

Check blower motor power andground circuits for open (circuits98 and GND).

Repair as necessary, then go totest no. 7 .

Less than 12V (not 0)or more than 17V

Blower has most likely enteredvoltage protection mode. Correctvoltage problem as necessary,then go to test no. 7 .

3 Check speed controlsignal at blowermotor.

Disconnect the blower motorconnector.

Turn ignition on.

Check voltage betweenconnector pin 6 and ground whilerotating the blower control switchfrom off to full speed. Thevoltage should be approximately0V (off) to 5V+ (high).

Voltage full range (0–5V+)

Go to test no. 4 .

Voltage stays at 0V Check speed control wire foropen circuit between blowermotor and FCU or ACU. If okay,check FCU/ACU. Repair/replaceas necessary, then go to testno. 7 .

4 Check for mechanicalobstruction/lockedrotor.

Remove the blower motor fromthe HVAC housing.

Check for obstruction preventingblower from turning.

Check if rotor spins freely byhand.

Obstruction Remove obstruction asnecessary, then go to test no.7.

Rotor locked Replace blower motor, then goto test no. 7 .

Neither Go to test no. 5 .




Blower Will Not Operate or Operates at Reduced Speed


5 Check voltage drop. Remove the blower motor fromthe HVAC housing.

Turn ignition on, set blowerspeed to high.

Check voltage on the power andground circuits by back-probingthe blower motor connector.Check between the positive andnegative battery posts.

NOTE: High voltage drop maycause the blower motor to entervoltage protection mode. This willcause the blower to operate atreduced speed and, if severeenough, may stop the bloweraltogether.

Less than 0.2V Go to test no. 6 .

More than 0.2V Locate source of high resistancecausing voltage drop. Repair asnecessary then go to test no. 7 .

6 Does the blowermotor operate at all?

—Yes

Check if blower motor feels hotand make sure there are noobstructions to airflow. If noobstructed airflow or blower feelshot, replace blower motor thengoto test no. 7 .

No Replace blower motor, then goto test no. 7 .




Table 12, Blower Will Not Operate or Operates at Reduced Speed

Diagnosis for Blower Speed is Not Available


1 Does blower operateat all? —

Yes Go to test no. 2 .

No Perform the tests in Table 12 .

2 Check feedbackspeed/diagnosticcircuit.

Check for open or short circuit inblower motor feedback speed/diagnostic circuit between theblower motor and the FCU/ACU.

Circuit is open orshorted

Repair blower motor feedbackspeed/diagnostic circuit then, goto test no. 3 .

Circuit okay Perform the tests in Table 12 .




Table 13, Diagnosis for Blower Speed is Not Available




08/16/2002 f831470a

1

4

6

2 3

5

1. Mode Actuator2. CDTC Temperature Sensor3. Evaporator Temperature Sensor4. Recirculation Actuator5. Blower Motor6. Temperature Actuator

Fig. 2, Cab HVAC Assembly

08/27/2002 f831539

2 3

4

1

1. CDTC Sensor2. Temperature Actuator3. Auxiliary Control Unit (ACU)4. Blower Motor

Fig. 3, Auxiliary HVAC Assembly




1

2

3 14

4

3

5

5

6

6

−

−

− −

− −

−

−

−

−

+

+

+

+

+

1

6+

+++++

CW

CC

W

08/27/2002 f831500

Fig. 4, Actuator Motor Pinouts




Documents

Heater and Air Conditioner, Blend Air System ...ww2.justanswer.com/uploads/budnshe/2010-04-15_023718_file.pdf · 15.04.2010 · NOTE: The actuator has no feedback to the FCU/ACU to