Lennox G24M3/4-100 User Manual

Page 30
Troubleshooting
HAS CONTROL RESET IGNITION
SEQUENCE FOUR TIMES?
HAS PRIMARY/SECONDARY
LIMIT AUTOMATIC RESET TIME
EXCEEDED 3 MINUTES?
FLAME STABILIZATION PERIOD.
HEATING SEQUENCE CONTINUED
NORMAL HEATING MODE ABNORMAL HEATING MODE
FLAME RECTIFICATION CURRENT CHECK
CAN FLAME BE PROVEN WITHIN 4
SECONDS AFTER GAS VALVE OPENS?
(0.15 microamps)
NO
FLAME PRESENT?
INDOOR BLOWER ON DELAY BEGINS
(45 seconds.)
PRIMARY AND SECONDARY LIMIT
SWITCHES CLOSED?
COMBUSTION AIR PRESSURE
SWITCH CLOSED?
LOW FLAME SIGNAL
(Does not affect operation of control)
LED #1 -- SLOW FLASH
LED #2 -- FAST FLASH
GAS VALVE DE-ENERGIZED.
COMBUSTION AIR BLOWER DE-ENERGIZED.
INDOOR BLOWER ON UNTIL SWITCH CLOSES.
LED #1 -- SLOW FLASH. LED #2 -- ON.
IS LIMIT SWITCH CLOSED?
GAS VALVE DE-ENERGIZED.COMBUSTION AIR BLOWER ON.
INDOOR BLOWER OFF WITH DELAY
LED #1 -- OFF. LED #2 -- SLOW FLASH.
HAS CAB SWITCH CLOSED IN 2.5 MINUTES?
15SECOND COMBUSTION AIR BLOWER PREPURGE
INITIATED BY CLOSED PRESSURE SWITCH.
YES
IGNITOR WARMUP -- 20 SECONDS.
4SECOND TRIAL FOR IGNITION.
GAS VALVE OPENS. IGNITOR ENERGIZED FOR
1 SECOND AFTER VALVE OPENS.
NO FLAME SENSED DURING THIS PERIOD.
GAS VALVE OFF. COMBUSTION AIR BLOWER ON.
INDOOR BLOWER OFF.
HAS CONTROL FAILED TO SENSE FLAME FOR
FIVE CONSECUTIVE TRIES DURING A SINGLE
HEAT DEMAND?
NO
YES
YES
NO
4 SECONDS
YES
NO
FLAME SIGNAL ABOVE 0.7 MICROAMPS?
NO
NO
YES
NO
ROLLOUT SWITCH CLOSED?
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.
NO
YES
NO
THERMOSTAT DEMAND SATISFIED.
LED #1 & #2 SIMULTANEOUS SLOW FLASHES.
COMB. AIR BLOWER CONTINUES 5SECOND
POST PURGE AFTER T'STAT DEMAND IS SATISFIED.
INDOOR AIR BLOWER COMPLETES SELECTED
OFF" DELAY BEFORE SHUTTING OFF.
NO
5MINUTE PRESSURE SWITCH
WATCHGUARD MODE.
INDOOR BLOWER ON ACB HEAT SPEED.
ACC. TERMINAL ENERGIZED
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
LIMIT SWITCH WATCHGUARD MODE.
GAS VALVE OFF. COMBUSTION AIR
BLOWER OFF.
INDOOR BLOWER OFF WITH DELAY
LED #1-- SLOW FLASH, LED #2 -- ON.
IS 60MINUTE RESET PERIOD
COMPLETE?
YES
IGNITION WATCHGUARD MODE. GAS VALVE OFF.
COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF WITH DELAY
LED #1-- ALT. SLOW FLASH, LED #2 -- ALT. SLOW FLASH.
IS 60MINUTE RESET PERIOD COMPLETE?

Lennox G24M3/4-100 Specifications

General

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