SURELIGHT Corp. 9710−L7 IGNITION SYSTEM Service … Manuals/Surelight.pdf · Page 1 1999 Lennox Industries Inc. ... G26 10 ... REFER TO INSTALLATION INSTRUCTIONS FOR CONTROL BOARD

1999 Lennox Industries Inc.

Corp. 9710L7

Service Literature

SURELIGHT IGNITION SYSTEM

Revised 92003

SURELIGHT and BASIC SURELIGHT IGNITION SYSTEM

IGENERALThe SureLight and Basic SureLight ignition system con

sists of a Lennox control board (figure1) and hot surface

ignitor . Figures 2 and 3 show the general location of the

control board in multi and downflow position units. See

table 2 for furnace model / igntion system matchup. Both

models are similar except the SureLight board has a desig

nated continuous blower speed and is protected by a

circuit breaker located on the control box. Terminal desig

nations are shown in table 3. The Basic SureLight board

will energize HEATH heating speed for continuous blower

and the control circuit is protected by an on board fuse. On

both models the board and ignitor work in combination to

ensure furnace ignition and ignitor durability. Both models

control all major furnace operations. Tables 4 and 5 (Sur

elight) and tables 6 and 7 (Basic Surelight) show jack plug

terminal designations. Both boards also feature two LED

lights for trouble shooting (see table 1 for diagnostic codes)

and two accessory terminals. Terminal ACC energizes

with the indoor blower on the SureLight board and terminal

EACH energizes with the indoor blower on the Basic Sur

elight. Terminal HTG ACC energizes when CAI is

energized on the SureLight board and terminal HUMN en

ergizes with CAI on the Basic SureLight board. The

SureLight board has a built in heating isolation relay. See

wiring diagram for heat anticipator settings.

The ignitor used for both models is made of durable silicon

nitride. Ignitor longevity is also enhanced by controlling the

temperature of the ignitor. The board finds the lowest ignitor

temperature which will successfully light the burner, thus in

creasing the life of the ignitor.

IMPORTANTIgnition control will not operate unless unit isproperly grounded. 120V supply must beinstalled with correct polarity.

CAUTION

Electrostatic discharge can affect electroniccomponents. Take precautions during furnaceinstallation and service to protect the furnaceselectronic controls. Precautions will help toavoid control exposure to electrostatic discharge by putting the furnace, the control andthe technician at the same electrostatic potential. Neutralize electrostatic charge by touchinghand and all tools on an unpainted unit surface,such as the gas valve or blower deck, before performing any service procedure.

ELECTROSTATIC DISCHARGE (ESD)

Precautions and Procedures

Table of Contents

I General Information 1. . . . . . . . . . . . . . . . . . . . . . . . .

Board Diagnostic Codes 2. . . . . . . . . . . . . . . . . . . . . . .

Board Terminal Designations 3. . . . . . . . . . . . . . . . . . .

II Operation 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

III Furnace Wiring and Operation Sequence 8. . . . . .

G23 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

80MGF 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G26 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GHR26 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G24M 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G40UH 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G50UH 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

80UHG 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

90UGF 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G27M 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G32 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G32V 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GHR32 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GHR32V 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operation Sequence Flow Chart 23. . . . . . . . . . . . . . . .

SureLight Board 23. . . . . . . . . . . . . . . . . . . . . . . . . . .

Basic SureLight Board 28. . . . . . . . . . . . . . . . . . . . . .

Troubleshooting Guide (both models) 32. . . . . . . . . . .

SURELIGHT INTEGRATED CONTROL BOARD

FIGURE 1

J58

J156

XFMRN

BASIC SURELIGHT INTEGRATED CONTROL BOARD

BOARD # 63K8901, 24L8501, 56L8301 and 97L4801BOARD # 12L6901 and 56L8401

Both model boards are equipped with two LED lights for troubleshooting. The diagnostic codes are listed below in table 1.

TABLE 1

DIAGNOSTIC CODESMAKE SURE TO ID LEDS CORRECTLY: REFER TO INSTALLATION INSTRUCTIONS FOR CONTROL BOARD LAYOUT.

LED #1 LED #2 DESCRIPTIONSIMULTANEOUS

SLOW FLASHSIMULTANEOUS

SLOW FLASHPower Normal operation

Also signaled during cooling and continuous fan.

SIMULTANEOUS FASTFLASH

SIMULTANEOUS FASTFLASH

Normal operation signaled when heating demand initiated at thermostat.

SLOW FLASH ON

Primary or Secondary limit open. Units with board 63K8901 or 24L8501 (SureLight) and units with board 12L6901 (Basic SureLight): Limit must close within 5trials for ignition or board goes into one hour limit Watchguard. Units with board

56L8301, 97L48 (SureLight) and 56L8401 and 10M9301 (Basic SureLight): Limitmust close within 3 minutes or board goes into one hour limit Watchguard.

OFF SLOW FLASH

Pressure switch open or has opened 5 times during a single call for heat; OR:Blocked inlet/exhaust vent; OR: Condensate line blocked; OR: Pressure switch

closed prior to activation of combustion air blower.

ALTERNATING SLOWFLASH

ALTERNATING SLOWFLASH

Watchguard burners fail to ignite.

SLOW FLASH OFF Flame sensed without gas valve energized.

ON SLOW FLASHRollout switch open. OR: 9 pin (SureLight) or 12 pin (Basic SureLight) connector

improperly attached.

ONONOFF

ONOFFON

Circuit board failure or control wired incorrectly.

FAST FLASH SLOW FLASH Main power polarity reversed. Switch line and neutral.

SLOW FLASH FAST FLASH Low flame signal (see note below). Replace flame sense rod.

ALTERNATING FASTFLASH

ALTERNATING FASTFLASH

Improper main ground or line voltage below 75 volts; OR: Broken ignitor; OR:Open ignitor circuit.

NOTE Slow flash equals 1 Hz (one flash per second). Fast flash equals 3 Hz (three flashes per second). Normal flame signal for SureLight control is 0.61

or greater microamps with a drop out signal of 0.20 or less microamps. Normal flame signal for Basic SureLight is 0.18 or greater micro amps with a dropout signal of 0.15 or less micramps.

TABLE 2

ModelSureLight Ignition System

Model 63K8901, 24L8501, 56L8301,97L4801

Basic SureLight Ignition SystemModel 12L6901, 56L8401, 10M9301

G23(X)

80MGF

G24M

G27M

G26 / GHR26

90UGF

G32Q/V

GHR32Q/V

G50UH

80UHG

G40UH

TABLE 3

IGNITION CONTROL BOARD TERMINAL DESIGNATIONS

SureLight Terminals Basic SureLight Terminals Function

ACB COOL COOLH Blower Cooling Speed 120V

ACB HEAT HEATH BlowerHeating Speed 120V

ACC EACH Accessory / Electronic Air Cleaner 120V

HTG ACC HUMH Heat Accessory / Humidifier 120V

24VAC HOT XFMRH Transformer 24V Hot

24VAC RTN XFMRN Transformer Neutral

HOT LINEH 120V Hot Input

NEUTRAL LINEN 120V Neutral

PARK (dead) PARK (dead) Alternate Speed Taps

TX 120V To Transformer

FLAME SENSE FLAME SENSE Flame Sense

HUMN Humdifier Neutral

EACN Electronic Air Cleaner Neutral

CIRN Blower Neutral

TABLE 4

SURELIGHT BOARD J156 (J2) TERMINAL DESIGNATIONS

PIN # FUNCTION

1 Ignitor

2 Not Used

3 Ignitor Neutral

4 Combustion Air Inducer Line Voltage

5 Not Used

6 Combustion Air Inducer Neutral

TABLE 5

SURELIGHT BOARD J58 (J1) TERMINAL DESIGNATIONS

PIN # FUNCTION

1 Primary Limit In

2 Gas Valve Common

3 Roll Out Switch Out

4 Gas Valve 24V

5 Pressure Switch In

6 Pressure Switch and Primary Limit Out

7 Not Used

8 Roll Out Switch In

9 Ground

TABLE 6

BASIC SURELIGHT BOARD J156 (J2) TERMINAL DESIGNATIONS

PIN # FUNCTION

1 Combustion Air Inducer Line

2 Ignitor Line

3 Combustion Air Inducer Neutral

4 Ignitor Neutral

TABLE 7

BASIC SURELIGHT BOARD J58 (J1) TERMINAL DESIGNATIONS

PIN # FUNCTION

1 Secondary Limit

2 Not Used

3 24V

4 Not Used

5 Rollout Switch In

6 24V

7 Primary Limit

8 Ground

9 Gas Valve In

10 Pressure Switch Out

11 Rollout Switch Out

12 Gas Valve Out

FIGURE 2

G40UH(X) HORIZONTAL POSITION

BASIC SURELIGHT CONTROLBOARD

FIGURE 3

G32V

SURELIGHT CONTROL BOARD

IIOPERATION (Both Models)

FAN TIMER CONTROL

The fan on time (during heat mode) of 45 seconds is notadjustable. Fan off time (time that the blower operates after

the heat demand has been satisfied) can be adjusted by

flipping the dip switches located on the SureLight integrated control. The unit is shipped with a factory fan off

setting of 90 seconds. Fan off time will affect comfort and is

adjustable to satisfy individual applications. There is nofanon or fanoff time during cool mode. Fan energizes

upon demand for cool and deenergizes when demand issatisfied. See figure 4 for fanoff time adjustment.

FIGURE 4

FANOFF TIME ADJUSTMENT

To adjust fanoff timing, flip dip switch (black) to desired setting.

60sec. 90sec. 120sec. 180sec.

ELECTRONIC IGNITIONOn a call for heat the control monitors the combustion airblower pressure switch. The control will not begin the heat

ing cycle if the pressure switch is closed (jumpered). Once

the pressure switch is determined to be open, the combustion air blower is energized. When the differential in the

pressure switch is great enough the pressure switch

closes and a 15second prepurge begins. If the pressureswitch is not proven within 21/2 minutes, the control goes

into WatchguardPressure Switch mode for a 5minute re

set period.

After the 15second prepurge period, the ignitor warms

up for 20 seconds,during which the gas valve opens at 19seconds for a 4 second trial for ignition. See figure 5 . The

ignitor energizes for the first second of the 4second trial.

BOARD 97L4801 and 10M9301 ONLY: ignitor energizesthe entire 4 second trial, or until flame is sensed (which

ever is first). If ignition is not proved during the 4secondperiod, the control will try four more times. After a total of

five trials for ignition (including the initial trial), the control

goes into WatchguardFlame Failure mode. After a60minute reset period, the control will begin the ignition

sequence again.

The control board has an added feature that prolongs thelife of the ignitor. After the first successful ignition, the con

trol lowers the ignitor temperature on successive calls forheat. The control continues to lower the ignitor tempera

ture until it finds the lowest temperature that will provide a

successful ignition. It finds this by ramping down until the

ignitor will not light, then steps up by 3 times. Lower tem

perature means a cooler ignitor which prolongs ignitor

life. This amount is used for 255 cycles . On the 256th call

for heat, the control will again ramp down until the lowest

ignitor temperature is determined and the cycle begins

again.

GAS VALVE

Gas valves used will be manufactured by White Rodgers

or Honeywell. The valves are internally redundant to as

sure safety shut off. The valve on the G27M, G32(V) and

GHR32(V) provides twostage heat. 24VAC terminals on

top of the valves are connected to wires from the SureLight

ignition control Jackplug J58 (some boards will have J1).

FLAME SENSING AND RECTIFICATION

The SureLight ignition system uses a sensing probe to

verify flame conditions through flame rectification. The

sensing probe functions quite differently from a thermo

couple in a standard furnace.

Flame rectification is the property of a gas flame which per

mits it to act as a DC current path between two metal

objects, when an AC voltage is applied between the two

objects that are enveloped in a gas flame. An AC voltage is

applied to the flame sensor and burner/burner crossover

by the SureLight circuitry. Electrons are discharged alter

nately from the burner/crossover to the sensor and back.

More electrons will hit the burner and crossover than sen

sor since the grounding area is so much larger. The end

result is a pulsating DC current flowing through the flame in

one direction (flame sensor to burner crossover) which is

of a larger magnitude than the current flowing in the oppo

site direction (burner crossover to flame sensor).This

pulsating DC current is the only type of signal which the

SureLight board will accept as proof of flame. See figures

6 , 7 and 8 .

IGNITOR

The SureLight ignitor is made of durable silicon nitride. Ig

nitor longevity is enhanced by controlling voltage to the

ignitor. The board finds the lowest ignitor temperature

which will successfully light the burner, thus increasing the

life of the ignitor. Due to this feature of the board, voltage

cannot be measured so ignitor must be ohmned. Ohm

value should be between 10.9 and 19.7. See figures 6 ,

7 and 8 for ignitor location.

DEMANDCAI

GAS VALVE

15

ON

OFF

38

IGNITOR

341

Pre Purge Ignitor Warmup Trial forIgnition

Post Purge

5 SEC80

*Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on OFF TIME" Setting.

INDOOR BLOWER

FIGURE 5

Blower On"Delay

SureLight Control Ignition Sequence

35

FLAME SENSORSURELIGHT IGNITOR

SureLight Ignitor and SensorG27M, G24M, 80MGF and 80UHG

FIGURE 6

GAP TO BURNER = 1/4" GAP TO BURNER = 1/4"

SURELIGHT IGNITOR

FLAME SENSOR

SureLight Ignitor and SensorG23(X),G26, 90UGF, GHR26, G32/V and GHR32/V

FIGURE 7


SureLight Ignitor and SensorG40UHG and G50UHG

FIGURE 8

SURELIGHT INGITOR

FLAME SENSOR


IIISEQUENCE OF OPERATION AND WIRING DIAGRAMAG23

DG40UH

EG50UH

FGHR26

G80MGF

H80UHG

I90UGF

Sequence of Operation G23X / 80MGF / G26 / GHR26 / 90UGF / 80UGH / G24MG40UH/G50UH 1 When there is a call for heat, W1 of the thermostat en

ergizes W of the furnace control with 24VAC.

2 S10 primary limit switch and S47 rollout switch areclosed. Call for heat can continued.

3 SureLight control energizes combustion air inducerB6. Combustion air inducerruns until S18 combustionair prove switch closes (switch must close within 21/2minutes or control goes into 5 minute WatchguardPressure Switch delay). Once S18 closes, a 15second prepurge follows.

4 SureLight control energizes ignitor. A 20secondwarmup period begins.

5 Gas valve opens for a 4second trial for ignition.

6 Flame is sensed, gas valve remains open for the heatcall.

7 After 45second delay, SureLight control energizes indoor blower B3.

8 When heat demand is satisfied, W1 of the indoor thermostat deenergizes W of the SureLight control whichdeenergizes the gas valve. Combustion air inducerB6 continues a 5second postpurge period, and indoor blower B3 completes a selected OFF time delay.

MGHR32

NGHR32V

Sequence of Operation G27M / G32 / G32V GHR32 / GHR32VIgnitor operation will vary between SureLight boards.

Boards 56L83, 24L85 and 63K89 will energize the ignitor

for the first second of the 4second ignition trial. Board

97L48 will energize the ignitor for the full 4second igntion

trial.

1 When there is a call for heat, W1 of the thermostat en

ergizes W of the furnace control with 24VAC.

2 SureLight control runs selfcheck for S10 primary limit

switch and S21 secondary limit switch normally

closed contacts. The control also checks S18 com

bustion air prove switch and S102 high fire pressure

switch normally open contacts.

3A Singlestage Mode, SingleStage Thermostat Sur

eLight control energizes combustion air inducer B6 on

high speed. Combustion air inducer runs until S102

high fire pressure switch closes (switch must close

within 21/2 minutes or control goes into 5 minute

WatchguardPressure Switch delay). A 15second

prepurge follows after S102 closes.

3B Twostage Mode, SingleStage Thermostat Sur


low speed. Combustion air inducer runs until combus

tion air inducer switch S18 closes (switch must close



prepurge follows once S18 closes.

3C Twostage Mode, Two Stage Thermostat Sur


low speed. Combustion air inducer runs until combus

tion air inducer switch S18 closes (switch will close



prepurge follows once S18 is closes.

4 SureLight control energizes ignitor. A 20second

warmup period begins.

5A Singlestage Mode, SingleStage Thermostat

Gas valve is energized on first stage heat (low). Gas

valve opens for a 4 second trial for ignition. Flame is

sensed. After 8 seconds from when gas valve opens,

valve energizes on second stage (high heat).

5B Twostage Mode, SingleStage Thermostat Gas

valve is energized on first stage. Gas valve opens for

a 4second trial for ignition. Signal is sent from control

module to twostage control board to begin W2 (sec

ondstage) ON delay.

5C TwoStage Mode, Two Stage Thermostat Gas

valve is energized on first stage only. Gas valve opens

for a 4second trial for ignition.

6 Flame is sensed, gas valve remains open for the heat

call.

7A Singlestage Mode, SingleStage Thermostat Af

ter 45second delay, indoor blower B3 is energized on

high heating speed.

7B Twostage Mode, SingleStage Thermostat Af

ter 45second delay, indoor blower B3 is energized on

low speed.

7C TwoStage Mode, Two Stage Thermostat After

45second delay, indoor blower B3 is energized on

low speed.

8A Twostage Mode, SingleStage Thermostat Sec

ond stage time on delay complete (8, 12, or 15

minutes). Gas valve opens, indoor blower B3 remains

energized on heating speed.

8B TwoStage Mode, Two Stage Thermostat Call

for second stage heat comes from indoor thermostat.

PROVE SWITCH WATCHGUARD(5 MINUTES)

COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF.

LED #1 OFFLED #2 SLOW FLASH

HIGHFIRE PROVESWITCH CLOSED?

GAS VALVE OFF.COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAY.LED #1 OFF

LED #2 SLOW FLASH(Sequence holds until pressure switchcloses or thermostat resets control.)

HEATING SEQUENCE OF OPERATION

NORMAL HEATING MODE ABNORMAL HEATING MODE

CONTROL SELFCHECK OKAY?

BURNER OFF?(CONTINUOUS FLAME CHECK)

NORMAL OPERATION:LED #1 SLOW FLASHLED #2 SLOW FLASH

YES

YES

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER DELAY OFF.

LED #1 ONLED #2 ON

(RESET CONTROL BY TURNING MAIN POWER OFF.)

POLARITY REVERSED.LED #1 FAST FLASHLED #2 SLOW FLASH

POWER ON

COMBUSTION AIR INDUCER ON FOR 1 SECOND.

ROLLOUT SWITCH CLOSED?

THERMOSTAT CALLS FOR HEAT:LED #1 FAST FLASHLED #2 FAST FLASH

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF WITH DELAY.LED #1 ON. LED #2 SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER ON HEATING SPEED.

LED #1 SLOW FLASHLED #2 OFF

NO

YES

NO

IS THEREPROPER GROUND?

IS VOLTAGEABOVE 75 VOLTS?

LOW VOLTAGE SIGNAL AT LED HOLDSUNTIL VOLTAGE RISES ABOVE 75 VOLTS.

NO

YESNO

SIGNAL IMPROPERGROUND AT LED.SIGNAL HOLDSUNTIL UNIT IS

PROPERLYGROUNDED.

NO

NO

CONTINUED NEXT PAGE

PRIMARY & SECONDARY LIMIT SWITCHES CLOSED?

COMBUSTION AIR INDUCER OFF.INDOOR BLOWER ON.LED #1 SLOW FLASH

LED #2 ON

NO

YES

NO

TWOSTAGE MODECALL FOR 1ST STAGE HEAT

TWOSTAGE MODESINGLE STAGE TSTAT

SINGLESTAGE MODEHIGH HEAT ONLY

COMBUSTION AIR INDUCERON LOW SPEED ( 2.5 MINUTES)

LOWFIRE PROVESWITCH CLOSED?

PREPURGE15 SECONDS

COMBUSTION AIR INDUCERON HIGH SPEED ( 2.5 MINUTES)

NONO

YES YES

YES

PROVE SWITCH CONTACTS OPEN?(HIGH AND LOW FIRE)

G26, GHR26, 90UGF, G24M, G23X, 80MGF,G27M, G32, G32V, GHR32, GHR32V and G50UH

SEQUENCE

G27M,G32, G32V,GHR32 and GRH32V

SEQUENCEONLY

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER ON.

LED #1 ALTERNATING FAST FLASHLED#2 ALTERNATING FAST FLASHCHECK FOR BROKEN IGNITOR OR

OPEN IGNITOR CIRCUIT

YES

POLARITYOKAY?

IS COMBUSTION AIR INDUCER ENERGIZED?(HTG ACC ENERGIZES WITH C.A.I.)

*G26, GHR26, 90UGF, G24M,G23X , 80MGF and G50UH

SEQUENCE ONLY




*IS COMBUSTION AIR INDUCER ENERGIZED?(HTG ACC TERMINAL IS ENERGIZED WITH C.A.B)

*HAS COMBUSTION AIR PROVE SWITCHCLOSED IN 2.5 MINUTES?

YES

*15SECOND COMBUSTION AIR INDUCERPREPURGE INITIATED BY CLOSED PROVE SWITCH.

YES

YES

HEATING SEQUENCE CONTINUED

IGNITOR WARMUP 20 SECONDS.

YES

4SECOND TRIAL FOR IGNITION. GAS VALVE OPENS. BOARDS 63K89, 24L85AND 56L83: IGNITOR ENERGIZED FOR1 SECOND AFTER VALVE OPENS.BOARD 97L48,: IGNITOR ENERGIZED THE FULL 4SECOND TRIAL FOR

IGNITION. NO FLAME SENSED DURING THIS PERIOD.

YES

FLAME STABILIZATION PERIOD.

4 SECONDS



TWOSTAGE MODECALL FOR 1st STAGE HEAT

GAS VALVE OPENHIGH AND LOW FIRE

MAIN GAS VALVE OPENLOW FIRE ONLY

MAIN GAS VALVE OPENLOW FIRE ONLYSECOND STAGETIME ON BEGINS

4 SECONDS

FLAME PRESENT?

YES

FLAME SIGNAL ABOVE 0.7 MICROAMPS?

YES

INDOOR BLOWER ON DELAY BEGINS. AFTER 45SECOND DELAY, ACB HEAT SPEED TERMINAL IS

ENERGIZED. ACC TERMINAL IS ENERGIZED.

YES

FLAME RECTIFICATION CURRENT CHECKCAN FLAME BE PROVEN WITHIN 4

SECONDS AFTER GAS VALVE OPENS?(0.15 microamps)

INDOOR BLOWERON LOW SPEED

INDOOR BLOWERON HIGH HEATING SPEED




CONTINUED NEXT PAGE

YES

*IS COMBUSTION AIRPROVE SWITCH OPEN?

PROVE SWITCH WATCHGUARD(5 MINUTES)

COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF.

LED #1 OFFLED #2 SLOW FLASH

NO

HAS CONTROL RESET IGNITIONSEQUENCE FOUR TIMES?

YES

NO

WATCHGUARD MODE. GAS VALVE OFF.COMBUSTION AIR INDUCER OFF.

INDOOR BLOWER OFF WITH DELAYLEDs SIGNAL WATCHGUARD FAILURE CODE.

IS 60MINUTE RESET PERIOD COMPLETE?

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER OFF.

HAS CONTROL FAILED TO SENSE FLAME FORFIVE CONSECUTIVE TRIES DURING A SINGLE

HEAT DEMAND?

LOW FLAME SIGNAL(Does not affect operation of control)

LED #1 SLOW FLASHLED #2 FAST FLASH

NO

NO

NO

DEMAND FOR HEAT SATISFIED.THERMOSTAT OPENS.



PRIMARY AND SECONDARY LIMITSWITCHES CLOSED?

COMBUSTION AIR PROVESWITCH CLOSED?

YES


YES

GAS VALVE DEENERGIZED.COMBUSTION AIR INDUCER DEENERGIZED.

INDOOR BLOWER ON UNTIL SWITCH CLOSES.LED #1 SLOW FLASH. LED #2 ON.

IS LIMIT SWITCH CLOSED?

YES

HAS PRIMARY/SECONDARY LIMIT RESET(see table 1 DIAGNOSTIC CODES for limit reset operation)

NO

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF WITH DELAY.LED #1 ON. LED #2 SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

NO

GAS VALVE DEENERGIZED.COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF WITH DELAYLED #1 OFF. LED #2 SLOW FLASH.

HAS CAB SWITCH CLOSED IN 2.5 MINUTES?

YESNO

15SECOND COMBUSTION AIR INDUCER PREPURGEINITIATED BY CLOSED PRESSURE SWITCH.




YES

NO

NO

5MINUTE PROVE SWITCHWATCHGUARD MODE.

THERMOSTAT DEMAND SATISFIED.

LED #1 & #2 SIMULTANEOUS SLOW FLASHES.

COMB. AIR INDUCER CONTINUES 5SECOND. POSTPURGE AFTER TSTAT DEMAND IS SATISFIED. IN

DOOR AIR BLOWER COMPLETES SELECTED OFF"DELAY BEFORE SHUTTING OFF. ACB HEAT SPEED,

HTG ACC AND ACC TERM. DEENERGIZE.

YES

YES

YES

INDOOR BLOWER ONHEAT SPEED?


PROVE SWITCH CLOSED?

CALL FOR 2nd STAGEHEAT (HIGH FIRE)

FROM THERMOSTAT

2nd STAGE ON DELAYON CONTROL BOARD

COMPLETE (8, 12 OR 15 MIN.)

YES

HIGH FIRE PROVE SWITCH CLOSED?

HIGH FIRE GAS VALVE OPEN? (8 SEC. DELAY)

NOYES YES

COMBUSTION AIR INDUCER ON HIGH SPEED?

NO




CONTROL CHECKS: FLAME PRESENCE, CLOSED PRIMARY& SECONDARY LIMITS, CLOSED PROVE SWITCHES,

CONTINUOUSLY CLOSED ROLLOUT SWITCHES (duringheating cycle).

SEE PREVIOUS SEQUENCES FOR FAILURE MODES.

GAS VALVE DEENERGIZED.

COMBUSTION AIR INDUCERPOSTPURGE 5 SECONDS.

INDOOR BLOWERSELECTED TIME OFF DELAY.

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE ABNORMAL COOLING MODE

IGNITION CONTROL MAIN POWER ON.

CONTROL SELF DIAGNOSTIC CHECK.IS CONTROL OPERATING NORMALLY?

YES

SIGNAL POLARITY REVERSED AT LED.

POWER ON

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF WITH NORMAL DELAY.

SIGNAL CIRCUIT BOARD FAILURE AT LED.INTERRUPT MAIN POWER TO RESET CONTROL.

YES

TURN INDUCER ON FOR 1 SECOND.

IS POLARITY REVERSED?

ROLLOUT SWITCH MONITORED CONTINUOUSLY.IS ROLLOUT SWITCH CLOSED?

CHECK FOR MAIN BURNER FLAME SENSE.IS MAIN BURNER FLAME OFF?

LED: SLOW FLASH RATE REMAINS UNCHANGEDTHROUGHOUT COOLING CYCLE.

THERMOSTAT CALLS FOR COOLING.

COMPRESSOR CONTACTOR AND SYSTEM FANENERGIZED WITH 0SECOND DELAY. ACB COOL

SPEED IS ENERGIZED. ACC TERMINAL IS ENERGIZED.

COMPRESSOR OFF.

THERMOSTAT OPENS.

SYSTEM FAN AND ACC. TERM. OFFWITH 0SECOND DELAY.

NO

YES

NO


SIGNAL CIRCUIT BOARD FAILURE AT LED.SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

NO


SIGNAL CIRCUIT BOARD FAILURE AT LED.SEQUENCE HOLDS UNTIL FLAME IS NOT SENSED.

NO

IS THEREPROPER GROUND?


LOW VOLTAGE SIGNAL AT LED HOLDSUNTIL VOLTAGE RISES ABOVE 75 VOLTS.

NOYES

NO

SIGNAL IMPROPERGROUND AT LED.SIGNAL HOLDSUNTIL UNIT IS

PROPERLYGROUNDED.

CONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATIONSURELIGHT CONTROL

LED: SLOW FLASH RATE REMAINSUNCHANGED THROUGHOUT SEQUENCE.

MANUAL FAN SELECTION MADE AT THERMOSTAT.CONTROL (G) ENERGIZES SYSTEM FAN AT ACBLOW SPEED. ACC. TERMINAL IS ENERGIZED.

THERMOSTAT CALLS FOR HEAT (W).


BOARD NO. 63K8901SYSTEM FAN DEENERGIZED. SYSTEM FANENERGIZES ON ACB HEAT SPEED AFTER

NORMAL DELAY.

THERMOSTAT OPENS. COMBUSTION AIRAND HTG ACC TERMINAL DEENERGIZE.

SYSTEM FAN SWITCHED TO ACB COOLSPEED. ACC. TERM. REMAINS ON.

THERMOSTAT OPENS.

BOARD 63K89: SYSTEM FAN OFF. ACC. TERM.OFF. (AFTER OFF DELAY COMPLETED).

MANUAL FAN SELECTION MADE AT THERMOSTAT.CONTROL (G) ENERGIZES SYSTEM FAN AT ACB

LOW SPEED. ACC. TERM. ENERGIZED.

NO YES

YESNO

HTG ACC. TERM. ENERGIZES WITH COMB. AIR BLOWER.

BOARD NO. 24L85, 56L83, 97L48SYSTEM FAN SWITCHES TO ACB HEAT SPEEDAFTER NORMAL DELAY (fan remains energized)

BOARDS 24L85, 56L83 AND 97L48:SYSTEM FAN SWITCHES TO

LOW SPEED AFTER NORMAL DELAY.(fan remains energized)

HEATING SEQUENCE OF OPERATION


CONTROL SELFCHECK OKAY?

BURNER OFF?(CONTINUOUS FLAME CHECK)

NORMAL OPERATION:LED #1 SLOW FLASHLED #2 SLOW FLASH

YES

YES

YES

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER DELAY OFF.

LED #1 ONLED #2 ON

(RESET CONTROL BY TURNING MAIN POWER OFF.)

POLARITY REVERSED.LED #1 FAST FLASHLED #2 SLOW FLASH

POWER ON



THERMOSTAT CALLS FOR HEAT:LED #1 FAST FLASHLED #2 FAST FLASH

IS COMBUSTION AIRPROVE SWITCH OPEN?


LED #1 ON. LED #2 SLOW FLASH.SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER ON HEATING SPEED.

LED #1 SLOW FLASHLED #2 OFF




NO

NO

YES

NO


LED SIGNALS WAITING ON CALL FROMTHERMOSTAT. CONTROL WILL NOT RESPOND

UNTIL VOLTAGE RISES ABOVE 75 VOLTS.

NO

NO

NO

IS COMBUSTION AIR INDUCER ENERGIZED?

HAS COMBUSTION AIR PROVE SWITCHCLOSED IN 2.5 MINUTES?

YES

YESPROVE SWITCH IS IN WATCHGUARD MODE.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF WITH DELAY.

LED #1 OFF. LED #2 SLOW FLASH.IS 5MINUTE RESET PERIOD COMPLETE?

NO

PRIMARY AND SECONDARY LIMIT SWITCH.CLOSED?

YES

YES

CONTINUED NEXT PAGE

COMBUSTION AIR INDUCER OFF.INDOOR BLOWER ON

LED #1 SLOW FLASH RATELED #2 ON

NO

YES

YES

NO

YES

G40UH and 80UHGONLY SEQUENCE



FLAME RECTIFICATION CURRENTCHECK. CAN FLAME BE PROVEN WITHIN4 SECONDS AFTER GAS VALVE OPENS?

(0.15 microamps)

FLAME PRESENT?

INDOOR BLOWER ON DELAY BEGINS(45 seconds.)

PRIMARY AND SECONDARY LIMITSWITCHES CLOSED?

COMBUSTION AIR PROVESWITCH CLOSED?

LOW FLAME SIGNAL(Does not affect operation of control)

LED #1 SLOW FLASHLED #2 FAST FLASH

GAS VALVE DEENERGIZED.COMBUSTION AIR INDUCER DEENERGIZED.

INDOOR BLOWER ON UNTIL SWITCH CLOSES.LED #1 SLOW FLASH. LED #2 ON.

IS LIMIT SWITCH CLOSED?

GAS VALVE DEENERGIZED.COMBUSTION AIR INDUCER ON.

INDOOR BLOWER OFF WITH DELAYLED #1 OFF. LED #2 SLOW FLASH.

HAS CAB SWITCH CLOSED IN 2.5 MINUTES?

15SECOND COMBUSTION AIR INDUCER PREPURGEINITIATED BY CLOSED PROVE SWITCH.

YES

IGNITOR WARMUP 20 SECONDS.

YES

4SECOND TRIAL FOR IGNITION.GAS VALVE OPENS. IGNITOR ENERGIZED FOR 1 SECOND

AFTER VALVE OPENS. BOARD 10M9301: IGNITORENERGIZED FULL 4 SECOND TRIAL.

NO FLAME SENSED DURING THIS PERIOD.

YES

FLAME STABILIZATION PERIOD.

GAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER OFF.

HAS CONTROL FAILED TO SENSE FLAME FORFIVE CONSECUTIVE TRIES DURING A SINGLE

HEAT DEMAND?




YES

4 SECONDS

YES

HAS CONTROL RESET IGNITIONSEQUENCE FOUR TIMES?

FLAME SIGNAL ABOVE 0.2 MICROAMPS?

YES

YES

YES


GAS VALVE POWER OFF. COMBUSTION AIR INDUCER POWER ON.

INDOOR BLOWER ONLED #1 ON. LED #2 SLOW FLASH.

SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESETAND MAIN POWER IS INTERUPTED OR

THERMOSTAT IS CYCLED OFF/ON FOR 1 TO 20 SEC.

YES

THERMOSTAT DEMAND SATISFIED.

LED #1 & #2 SIMULTANEOUS SLOW FLASHES.

COMB. AIR INDUCER CONTINUES 5SECONDPOST PURGE AFTER TSTAT DEMAND IS SATISFIED.

INDOOR AIR BLOWER COMPLETES SELECTEDOFF" DELAY BEFORE SHUTTING OFF.

YES

NO

5MINUTE PROVE SWITCHWATCHGUARD MODE.

YES

IS THERE A PROPER GROUND?

IS VOLTAGE ABOVE 75 VOLTS?

IS IGNITOR INTACT AND CONNECTED?

LEDS SIGNALALTERNATINGFAST FLASH

NO YES

YESYES

YES

YES

NO

NO

NO

NO

NO

NO

NO

NO

YES

YES

NO

NO

NO

NO

YES

YES

HAS PRIMARY SECONDARYLIMIT RESET (CLOSED)

WITHIN 3 MINUTES?

LIMIT SWITCHWATCHGUARD

MODE. GAS VALVEOFF. COMB. AIR INDUCER OFF.

INDOOR BLOWEROFF WITH DELAY.

LED#1SLOWFLASH LED#2 ON.

IS 60MINUTE RESET PERIOD

COMPLETE?

YES

COOLING SEQUENCE OF OPERATION

NORMAL COOLING MODE ABNORMAL COOLING MODE

IGNITION CONTROL MAIN POWER ON.

CONTROL SELF DIAGNOSTIC CHECK.IS CONTROL OPERATING NORMALLY?

YES

SIGNAL POLARITY REVERSED AT LED.

POWER ON


SIGNAL CIRCUIT BOARD FAILURE AT LED.INTERRUPT MAIN POWER TO RESET CONTROL.

YES


ROLLOUT SWITCH MONITORED CONTINUOUSLY.IS ROLLOUT SWITCH CLOSED?

CHECK FOR MAIN BURNER FLAME SENSE.IS MAIN BURNER FLAME OFF?

LED: SLOW FLASH RATE REMAINS UNCHANGEDTHROUGHOUT COOLING CYCLE.


COMPRESSOR CONTACTOR AND SYSTEM FANENERGIZED WITH 0SECOND DELAY

(COOLING SPEED). EACH TERM. ENERGIZED.

COMPRESSOR OFF.

THERMOSTAT OPENS.

SYSTEM FAN AND ACC. TERM. OFFWITH 0SECOND DELAY.

NO

NO


SIGNAL ROLLOUT SWITCH OPEN AT LED.SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.

GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.INDOOR BLOWER OFF WITH NORMAL DELAY.SIGNAL UNWANTED FLAME SENSED AT LED.

SEQUENCE HOLDS UNTIL FLAME IS NOT SENSED.


LED SIGNALS WAITING ON CALL FROMTHERMOSTAT. CONTROL WILL NOT RESPOND

UNTIL VOLTAGE RISES ABOVE 75 VOLTS.

YES

YES

YES

NO

NO

NO

SURELIGHT CONTROLCONTINUOUS HEAT SPEED FAN SEQUENCE OF OPERATION

LED: SLOW FLASH RATE REMAINSUNCHANGED THROUGHOUT SEQUENCE.

MANUAL FAN SELECTION MADE AT THERMOSTAT.CONTROL (G) ENERGIZES SYSTEM FAN AT HEATH

HEAT SPEED. EACH TERMINAL IS ENERGIZED.

THERMOSTAT CALLS FOR HEAT (W).

THERMOSTAT CALLS FOR COOLING.THERMOSTAT OPENS.

SYSTEM FAN SWITCHED TO COOLH SPEED.EACH TERM. REMAINS ON.

THERMOSTAT OPENS.

CONTROL (G) ENERGIZES SYSTEM FAN AT HEATHHEAT SPEED. EACH TERM. ENERGIZED.

NO YES

YESNO

HUMH TERM. ENERGIZES WITH COMB. AIR INDUCER.

SYSTEM FAN REMAINS ON HEATHHEATING SPEED.

SYSTEM FAN REMAINS ON HEATHHEATING SPEED.

HUMH TERM. DEENERGIZES WITH COMB. AIR INDUCER

SURELIGHT TROUBLE SHOOTING GUIDE

UPON INITIAL POWER UP, REMOVE ALL THERMOSTAT DEMANDS TO THE UNIT

PROBLEM: 1 UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE

Condition Possible Cause Corrective Action / Comments

1.1

Both diagnostic lights fail to lightup.

1.1.1

Main voltage 120V not supplied tounit.

ACTION 1 Check 120V main voltage.Determine cause of main power failure.

LED#1OffLED#2Off

1.1.2

Miswiring of furnace or improper connections.

ACTION 1 Check for correct wiring of 120V topower make up box and transformer.

ACTION 2 Check 24V wiring to control board.

1.1.3

Circuit breaker tripped or fails toclose.

ACTION 1 Replace circuit breaker if it is resetbut does not have continuity.

ACTION 2 If circuit breaker still trips, check forshort.

1.1.4

Door interlock switch failure.

ACTION 1 Check that door switch is activatedwhen door is closed.

ACTION 2 Check wire connections to switch,replace loose connectors.

ACTION 3 Check continuity of switch in closedposition. Replace if defective.

1.1.5

Transformer Failure.

ACTION 1 Check that transformer output is24V. Replace if defective.

1.1.6

Failed control board.

ACTION 1 If all the above items have beenchecked, replace board.

1.2

Diagnostic lights flash the rollout

code.

1.2.1

Rollout switch open.

ACTION 1 Manually reset the rollout switchby pushing the top button.

ACTION 2 Determine the cause of the rolloutswitch activation before leaving furnace.code.

LED#1 O

1.2.2

Rollout switch failure.

ACTION 1 Check continuity across rolloutswitch. Replace rollout switch if switch is reset

but does not have continuity.

LED#1On,

LED#2Slow Flash1.2.3

Mi i i i ti t ACTION 1 Check wiring connections to switchLED#2 Slow Flash

Miswiring or improper connections atrollout switch.

ACTION 1 Check wiring connections to switch.

1.2.4

Pin connector failure

ACTION 1 Check pin connector for properconnection to control board.

ACTION 2 Check continuity of the multi plugpin.

1.3

On initial powerup the comb. airblower does not energize.blower does not energize. Diagnostic lights flash the reversepolarity code.

1.3.1

120V main power polarity reversed.

ACTION 1 Check the 120V has line and neutralcorrectly input into control.ACTION 2 Reverse the line and neutral at the120V field connection.

LED#1Fast Flash,LED#2Slow Flash.

120V field connection.

1.4

On initial power up the combustionair blower does not energize.

Diagnostic lights flash normal power on operation.

1.4.1

Open combustion air blower motorcircuit.

ACTION 1 Check for 120V to combustion airblower. If no power, check wire and connec

tions.

er on operation.

LED#1Slow FlashLED#2Slow Flash

1.4.2

Failed combustion air blower motor.

ACTION 1 If power is present at blower, replaceblower.

PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE


1.5

On initial powerup the combustionair blower remains energized.

Di ti li ht fl h th i

1.5.1

Improper ground to the unit.

ACTION 1 Check that the unit is properlyground.ACTION 2 Install a proper main ground to theunitg

Diagnostic lights flash the impropermain ground.

1.5.2

6Pin connector is improperly attached to the circuit board.

ACTION 1 Check 6pin connector for properinstallation. Correctly insert connector into control.

LED#1Alternating Fast FlashLED#2Alternating Fast Flash

1.5.3

Line voltage is below 75V.

ACTION 1 Check that the line voltage is above75V. Determine cause of voltage drop and supplycorrect voltage to the control.

PROBLEM 2: UNIT FAILS TO OPERATE IN THE COOLING OR HEATING MODE, BUT COMBUSTIONAIR BLOWER OPERATES CONTINUOUS. UNITS WITH CONTROL BOARDS DATE CODED AFTER

NOV. 1 1997, WILL OPERATE IN COOLING BUT NOT IN THE HEATING MODE, WITH COMBUSTIONAIR BLOWER CYCLING 5 SECONDS ON 55 SECONDS OFF.


2.1

On initial powerup the combustionair blower remains energized. Diagnostic lights flash the impropermain ground. Units with control boards datecoded after Nov 1 1997; combustion

2.1.1

Open ignitor circuit.

ACTION 1 Check for correct wiring and looseconnections in the ignitor circuit. Check multplug connections for correct installation.

coded after Nov.1 1997; combustionair blower will cycle 5 seconds on 55seconds off.

LED#1Alternating Fast FlashLED#2Alternating Fast Flash

2.1.2

Broken or failed ignitor.

ACTION 1 Unplug ignitor and read resistanceacross ignitor. If resistance does not read between 10.9 and 19.7 ohms, replace the ignitor.

PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOESNOT ENERGIZE


3.1

Unit operates with a cooling or continuous fan demand. Combustion air blower will not startwith a Heating demand. Diagnostic lights flash the limit failure

d

3.1.1

Primary or secondary (if equipped )limit open.

ACTION 1 Check continuity across switch(es).Switches reset automatically upon cool down.ACTION 2 Check for restrictions on blower inletair (including filter) and outlet air. Determinecause for limit activation before placing unit backin operation.

g gmode.

LED#1Slow Flash,LED#2On

3.1.2

Miswiring of furnace or improper connections at limit switch(es).

ACTION 1 Check for correct wiring and looseconnections. Correct wiring and/or replace anyloose connections.

3.2

Unit operates with a cooling and continuous fan demand. Combustion air blower will not startwith a Heating demand. Diagnostic lights flash the pressure

3.2.1

Miswiring of furnace or improper connections to combustion air blower.


Diagnostic lights flash the pressureswitch failure code.

LED#1Off,LED#2Slow Flash

3.2.2

Pressure switch stuck closed.

ACTION 1 Check that the pressure switch isopen without the combustion air blower operating. Replace if defective.

PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOESNOT ENERGIZE (CONT.).

Condition Possible Cause Corrective Action/Comments

3.3

Unit operates with a cooling and continuous fan demand. Combustion air blower will not startwith a Heating demand. Diagnostic lights flash the pressureswitch failure code 2 5 minutes after

3.3.1

Miswiring of furnace or improper connections to combustion air blower.


switch failure code 2.5 minutes afterheating demand.

LED#1Off, LED#2Slow Flash

3.3.2

Combustion air blower failure.

ACTION 1 If there is 120V to combustion airblower and it does not operate, replace combustion air blower.

PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER ENERGIZES, IGNITOR IS NOT ENERGIZED.


4.1

Unit operates with a cooling andcontinuous fan demand. Combustion air blower energizeswith a heating demand

4.1.1

Pressure switch does not close dueto incorrect routing of the pressure

switch lines.

ACTION 1 Check that the pressure switch linesare correctly routed. Correctly route pressureswitch lines.

with a heating demand. Diagnostic lights flash the pressureswitch failure code 2.5 minutes afterheating demand.

4.1.2

Pressure switch does not close dueto obstructions in the pressure lines.

ACTION 1 Remove any obstructions from thethe pressure lines and/or taps.

g

LED#1Off

4.1.3

Pressure switch lines damaged

ACTION 1 Check pressure switch lines forleaks. Replace any broken lines.

LED#1 OffLED#2Slow Flash 4.1.4

Condensate in pressure switch line.

ACTION 1 Check pressure switch lines for condensate. Remove condensate from lines. Checkthat the condensate lines are located correctly.

4.1.5

Pressure switch does not close dueto a low differential pressure across

the pressure switch.

ACTION 1 Check the differential pressure

across the pressure switch. This pressure

should exceed the set point listed on the

switch.

ACTION 2 Check for restricted inlet and ex

haust vent. Remove all blockage.

ACTION 3 Check for proper vent sizing and

run length. See installation instructions.

4.1.6

Wrong pressure switch installed inthe unit, or pressure switch is out of

calibration.

ACTION 1 Check that the proper pressureswitch is installed in the unit. Replace pressureswitch if necessary.

4.1.7

Miswiring of furnace or improper connections at pressure switch.


4.1.8

Pressure switch failure.

ACTION 1 If all the above modes of failure havebeen checked, the pressure switch may havefailed. Replace pressure switch and determine ifunit will operate.

PROBLEM 5: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER ENERGIZES, IGNITOR IS ENERGIZED.


5.1

Unit operates with a cooling and

continuous fan demand.

Combustion air blower energizes

5.1.1

Check that gas is being supplied tothe unit.

ACTION 1 Check line pressure at the gas valve.Pressure should not exceed 13" WC for both natural and propane. Line pressure should read aminimum 4.5" WC for natural and 8.0"WC for propane.

Combustion air blower energizes

with Heating demand.

Ignitor is energized but unit fails to

light.

5.1.2

Miswiring of gas valve or loose connections at multipin control amp

plugs or valve.


LED#1Alternating Slow Flash

LED#2Alternating Slow Flash

5.1.3

Defective gas valve or ignition control.

ACTION 1 Check that 24V is supplied to the gasvalve approximately 35 seconds after heat demand is initiated.ACTION 2 Replace the valve if 24V is suppliedbut valve does not open.ACTION 3 Replace the control board if 24V isnot supplied to valve.

PROBLEM 6: BURNERS LIGHT WITH A HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY


6.1

Burners fire with a heating demand. Burners light but unit shuts off prior

6.1.1

Wrong concentric vent kit used forterminating the unit.

ACTION 1 Check vent termination kit installed.11/2" dia. concentric vent (kit60G77) for 50 and75 inputs and 2" dia. concentric vent (kit 33K97)for 100 &125 inputs.

Burners light but unit shuts off priorto satisfying Tstat demand. Diagnostic lights flash the pressureswitch code.

6.1.2

Condensate drain line is not drainingproperly.

ACTION 1 Check condensate line for propervent slope, and any blockage. Condensateshould flow freely during operation of furnace.Repair or replace any improperly installed condensate lines.

LED#1OffLED#2Slow Flash

6.1.3

Low pressure differential at the pressure switch.

ACTION 1 Check for restricted vent inlet or exhaust. Remove all blockage.ACTION 2: Check for proper vent sizing. Seeinstallation instructions.

6.2

Combustion air blower energizeswith a heating demand.

B li ht b t f il t t lit

6.2.1

Sensor or sense wire is improperlyinstalled.

ACTION 1 Check that sensor is properly located and that the sense wire is properly attached to both the sensor and the control.

Burners light but fail to stay lit. After 5 tries the control diagnosticsflash the watchguard burners failed toignite code.

6.2.2

Sensor or sense wire is broken.

ACTION 1 Check for a broken sensor.ACTION 2 Test continuity across the sensewire. If wire or sensor are damaged replace thecomponent.ignite code.

LED#1Alternating Slow FlashLED#2Alternating Slow Flash

6.2.3

Sensor or sensor wire is grounded tothe unit.

ACTION 1 Check for resistance between thesensor rod and the unit ground.ACTION 2 Check for resistance between thesensor wire and the unit ground.ACTION 3 Correct any shorts found in circuit.

6.2.4

Control does not sense flame.

ACTION 1 Check the microamp signal fromthe burner flame. If the microamp signal is below 0.70 microamps, check the sense rod forproper location or contamination.ACTION 2 Replace, clean, or relocate flamesense rod. If rod is to be cleaned, use steelwool or replace sensor. DO NOT CLEAN RODWITH SAND PAPER. SAND PAPER WILLCONTRIBUTE TO THE CONTAMINATIONPROBLEM. NOTE: Do not attempt to bendsense rod.

PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY (CONT.)


6.3

Combustion air blower energizeswith a heating demand. Burners light. Rollout switch trips during theheating demand. Diagnostic lights flash rollout failure.

6.3.1

Unit is firing above 100% of thenameplate input.

ACTION 1 Check that the manifold pressurematches value listed on nameplate. See installation instructions for proper procedure.ACTION 2 Verify that the installed orifice sizematch the size listed on the nameplate or installation instructions.ACTION 3 Check gas valve sensing hose to insure no leaks are present.ACTION 4 Check the input rate to verify ratematches value listed on nameplate.ure.

LED#1OnLED#2Slow Flash

6.3.2

Gas orifices leak at the manifold connection.

ACTION 1 Tighten orifice until leak is sealed.NOTE: Be careful not to strip orifice threads. ACTION 2 Check for gas leakage at the threadedorifice connection. Use approved method forleak detection (see unit instructions).

6.3.3

Air leakage at the connections between the primary heat exchanger,

secondary heat exchanger, and combustion air blower.

ACTION 1 Check for air leakage at all joints inthe heat exchanger assembly. Condition willcause high CO2 with high CO.ACTION 2 Seal leakage if possible, replaceheat exchanger if necessary, tag and return heatexchanger to proper Lennox personnel.

6.3.4

Insufficient flow through the heat exchanger caused by a sooted or re

stricted heat exchanger.

ACTION 1 Check for sooting deposits or otherrestrictions in the heat exchanger assembly.Clean assembly as outlined in instruction manual.ACTION 2 Check for proper combustion. Seetable 8 or 9 for proper CO2. CO should measurebelow .04% (400PPM) in an airfree sample offlue gases for either NG or LP.

6.3.5

Burners are not properly located inthe burner box.

ACTION 1 Check that the burners are firing intothe center of the heat exchanger openings. Correct the location of the burners if necessary.

6.4

Combustion air blower energizeswith a heating demand. Burners light roughly and the unitfails to stay lit. Diagnostic lights flash watchguardflame failure.

6.4.1

Recirculation of flue gases. This condition causes rough ignitions and operation. Problem is characterized by

nuisance flame failures.

ACTION 1 Check for proper flow of exhaustgases away from intake vent. Remove any obstacles in front of the intake and exhaust ventwhich would cause recirculation.ACTION 2 Check for correct intake and exhaustvent installation. See instructions

flame failure.


6.4.2

Improper burner crossovers

ACTION 1 Remove burner and inspect thecrossovers for burrs, or any restriction or ifcrossover is warped. Remove restriction or replace burners.

PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY (CONT.)

6.5

Combustion air blower energizeswith a heating demand. Burners light. Diagnostic lights flash watch guardflame failure. NOTE" Unit might go into 60 minute Watchguard mode depending onintermittent nature of sensor signal.


6.5.1

Loose sensor wire connection causesintermittent loss of flame signal.

ACTION 1 Check that the sensor is properly located.ACTION 2 Check that the sense wire is properly attached to both the sensor and the control.Pay extra attention to the pin connectors.

PROBLEM 7: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE


7.0

Unit operates correctly but thediagnostic lights flash low flamesense code

7.1.1

Sense rod is improperly located onthe burner.

ACTION 1 Check the sense rod for proper location on the burner. Properly locate the sense rodor replace if rod cannot be located correctly.

sense code.

LED#1Slow FlashLED#2Fast Flash

7.1.2

Sense rod is contaminated.

ACTION 1 Check sense rod for contaminationor coated surface. Clean the sense rod with steelwool or replace sensor. DO NOT USE SAND PAPER TO CLEAN ROD. SAND PAPER WILLCONTRIBUTE TO THE CONTAMINATIONPROBLEM.

PROBLEM 8: INDOOR BLOWER FAILS TO OPERATE IN COOLING, HEATING, OR CONTINUOUSFAN MODE


8.0

Indoor blower fails to operate incontinuous fan, cooling, or heatingmode.

8.1.1

Miswiring of furnace or improper connections at control or indoor blower

motor.

ACTION 1 Correct wiring and/or replace anyloose connections. Check for correct wiring andloose connections.

8.1.2

120V is not being supplied to the indoor air blower or blower motor fail

ure.

ACTION 1 Check for 120V at the various callsfor indoor blower by energizing "Y", "G", and "W"individually on the low voltage terminal strip.Note that when "W is energized, the blower isdelayed 45 seconds. If there is 120V to each motor tap but the blower does not operate, replacethe motor.

8.1.3

Defective control board

ACTION 1 If there is not 120V when "Y", "G", or"W" is energized, replace the control.

PROBLEM 9: RF STATIC DURING TIME FOR IGNITION


9.0

AM radio interference.

9.1.2

Ignitor operationACTION 1 Call Technical Support, Dallas.

TABLE 8

80% EFFICIENCY MODELS

CO2 AT *STEADY STATE OPERATION

UNIT NATURAL PROPANE

G23(X) 6.5% 8.5% 8.0% 9.5%

G24M 6.0% 8.0% 6.5% 8.5%

80MGF 6.0% 8.0% 6.5% 8.5%

80UHG 6.0% 8.0% 6.5% 8.5%

**G27M 6.0% 8.5% N/A

G40/50UH (X)24A45 4.5% 6.5% 5.8% 7.8%

G40/50UH(X)36A070 5.8% 7.8% 6.8% 7.8%

G40/50UH(X)36B0906 2% 8 2% 6 7% 8 6%

G40/50UH(X)48B0906.2% 8.2% 6.7% 8.6%

G40/50UH(X)48C110 5.9% 7.9% 7.5% 9.5%

* Furnace firing at least 15 minutes.

** Furnace firing on high fire.

TABLE 9

90% EFFICIENCY MODELS

CO2 AT *STEADY STATE OPERATION

UNITMIN VENT MAX VENT

UNITNATURAL PROPANE NATURAL PROPANE

G26 6.0% 8.0% 7.0% 9.0% 6.0% 8.0% 7.0% 9.0%

GHR26 6.0% 8.0% 7.0% 9.0% 6.0% 8.0% 7.0% 9.0%

90UGF 6.0% 8.0% 7.0% 9.0% 6.0% 8.0% 7.0% 9.0%

**G32Q/V 6.9% 8.4% 7.5%9.0% 7.3% 8.8% 8.2%9.5%

**GHR32Q/V 6.0% 8.0% 7.0% 9.0% 6.0% 8.0% 7.0% 9.0%

* Furnace firing at least 15 minutes.

** Furnace firing on high fire.

SERVICE NOTES

SureLight Ignition SystemDiagnostic Code TableBoard Terminal DesignationsOperationWiring Diagrams and Sequence of OperationFlow ChartTroubleshooting

Documents

SURELIGHT Corp. 9710−L7 IGNITION SYSTEM Service … Manuals/Surelight.pdf · Page 1 1999 Lennox Industries Inc. ... G26 10 ... REFER TO INSTALLATION INSTRUCTIONS FOR CONTROL BOARD