Lennox G24M3/4-100 User Manual

Page 29
Troubleshooting
SIGNAL IMPROPER
GROUND AT LED.
SIGNAL HOLDS
UNTIL UNIT IS
PROPERLY
GROUNDED.
HEATING SEQUENCE OF OPERATION
NORMAL HEATING MODE ABNORMAL HEATING MODE
CONTROL SELF-CHECK OKAY?
BURNER OFF?
(CONTINUOUS FLAME CHECK)
NORMAL OPERATION:
LED #1 -- SLOW FLASH
LED #2 -- SLOW FLASH
YE
S
YES
YES
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER DELAY OFF.
LED #1 ON
LED #2 ON
(RESET CONTROL BY TURNING MAIN POWER OFF.)
POLARITY REVERSED.
LED #1 -- FAST FLASH
LED #2 -- SLOW FLASH
POWER ON
COMBUSTION AIR BLOWER ON FOR 1 SECOND.
TURN INDUCER ON FOR 1 SECOND.
IS POLARITY REVERSED?
ROLLOUT SWITCH CLOSED?
THERMOSTAT CALLS FOR HEAT:
LED #1 -- FAST FLASH
LED #2 -- FAST FLASH
IS COMBUSTION AIR
PRESSURE SWITCH OPEN?
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 -- ON. LED #2 -- SLOW FLASH.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.
GAS VALVE OFF. COMBUSTION AIR BLOWER ON.
INDOOR BLOWER ON HEATING SPEED.
LED #1 -- SLOW FLASH
LED #2 -- OFF
GAS VALVE OFF.
COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 OFF
LED #2 SLOW FLASH
(Sequence holds until pressure switch
closes or thermostat resets control.)
YES
NO
IS THERE
PROPER GROUND?
IS VOLTAGE
ABOVE 75 VOLTS?
LOW VOLTAGE SIGNAL AT LED HOLDS
UNTIL VOLTAGE RISES ABOVE 75 VOLTS.
YES
IS COMBUSTION AIR BLOWER ENERGIZED?
(HTG. ACC. ENERGIZED WITH CAB.)
HAS COMBUSTION AIR PRESSURE
SWITCH CLOSED IN 2.5 MINUTES?
YES
PRESSURE SWITCH WATCHGUARD MODE.
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF WITH DELAY.
LED #1 -- OFF. LED #2 -- SLOW FLASH.
IS 5MINUTE RESET PERIOD COMPLETE?
15SECOND COMBUSTION AIR BLOWER PREPURGE
INITIATED BY CLOSED PRESSURE SWITCH.
CONTINUED NEXT PAGE
NO
NO
NO
NO
NO
NO
YES
YES
YES
NO

Lennox G24M3/4-100 Specifications

General

Brand	Lennox
Model	G24M3/4-100
Category	Furnace
Language	English