Troubleshooting: Heating Sequence Of Operation - COMFORT-AIRE Century GUH80C Series Service Manual

Troubleshooting: Heating Sequence of Operation

NORMAL HEATING MODE
CONTROL SELF-CHECK OKAY?
IS THERE A PROPER GROUND?
ROLLOUT SWITCH CLOSED?
NO
NORMAL OPERATION:
THERMOSTAT CALLS FOR HEAT:
PRIMARY LIMIT SWITCH. CLOSED?
PRESSURE SWITCH OPEN?
IS COMBUSTION AIR INDUCER
HAS COMBUSTION AIR PRESSURE
SWITCH CLOSED IN 2.5 MINUTES?
CONTINUED NEXT PAGE
508096-01
HEATING SEQUENCE OF OPERATION
POWER ON
YES
IS POLARITY CORRECT?
YES
YES
IS VOLTAGE
ABOVE 70 VOLTS?
YES
YES
BURNER OFF?
YES
LED SLOW FLASH
YES
LED SLOW FLASH
YES
YES
IS COMBUSTION AIR
YES
ENERGIZED?
YES
YES
ABNORMAL HEATING MODE
GAS VALVE OFF. COMBUSTION AIR INDUCER OFF.
NO
(RESET CONTROL BY TURNING MAIN POWER OFF.)
NO
LED FLASHES CODE 1 - POLARITY
NO
LED FLASHES CODE 2 - IMPROPER
NO
LED FLASHES CODE 13 - LOW LINE VOLTAGE.
CONTROL WILL NOT RESPOND TO A CALL FOR
HEATING UNTIL VOLTAGE RISES ABOVE 75 VOLTS.
LED FLASHES CODE 8 - ROLLOUT SWITCH OPEN.
NO
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES
AND POWER IS RESET OR T'STAT IS INTERRUPTED
LED FLASHES CODE 12 - FLAME SENSED
NO
WITHOUT GAS VALVE ENERGIZED.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.
INDOOR BLOWER ON HEATING SPEED.
NO
NO
LED FLASHES CODE 9 - PRESSURE SWITCH FAILED
NO TO CLOSE OR OPENED DURING HEAT DEMAND.
PRESSURE SWITCH IS IN WATCHGUARD MODE. GAS
VALVE OFF. COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAY. IS 5 MINUTE
RESET PERIOD COMPLETE?
Issue 2037
INDOOR BLOWER DELAY OFF.
LED SLOW FLASH
REVERSED.
GROUND.
INDOOR BLOWER ON.
FOR MINIMUM OF 1 SECOND.
LED FLASHES CODE 7 - PRIMARY
LMIT OPEN. COMBUSTION AIR
INDUCER OFF.I NDOOR BLOWER ON
LED FLASHES CODE 11 - PRESSURE
SWITCH CLOSED.
GAS VALVE OFF COMBUSTION AIR
INDUCER OFF. INDOOR BLOWER
OFF WITH DELAY.
(Sequence holds until pressure switch
opens or thermostat resets control.)
YES
Page 28 of 31