Turn thermostat
to call for heat.
30 second minimum
purge.
Does ignition module
get power (24 VAC
nominal)?
· Check line voltage power.
· Check low voltage transformer.
· Check limit controller.
· Check air proving switch (if used).
· Check thermostat.
· Check wiring.
· Check for 24 VAC across valve terminals on ignition module during trial for ignition timing.
If no voltage, replace ignition module.
· Check electrical connections between ignition module and gas control.
If OK, replace gas control.
· Check igniter position.
· Check gas pressure to main burner.
· Check air proving switch.
· Replace ignition module.
YES
YES
YES
YES
YES
YES
NO
NO
Igniter warms up and
glows red.
Main burner lights.
Confirm that 120V hot lead connects to L1
and 120V neutral lead connects to L2.
Check and correct wiring fuse
or circuit breaker.
NO
NO
NO
YES
Check for 120 VAC across hot surface
igniter terminals.
Check wires to igniter.
If OK, replace igniter.
Replace ignition module.
NO
START
NOTE: Before troubleshooting, become familiar with
First Start-up procedures.
FWF64N
NOTE: If ignition module goes into lockout, reset system.
· Check continuity of ground wire and ground path from main burner to GND (BURNER)
terminal of ignition module.
· Confirm that 120 VAC hot lead is connected to L1 and 120 VAC neutral lead is connected to L2.
· Check that burner flame covers igniter/sensor or sensor.
· Check insulation on igniter/sensor leads.
· Check igniter/sensor or flame rod for contamination or damage. Replace if necesssary.
· Check insulation on sensor leads and check sensor position.
If checks are OK, replace ignition module.
NOTE: System failure after main flame lights has a low probability of being the ignition module.
Main burner remains
powered and lit.
NO
YES
YES
NOTE: If ignition module goes into lockout, reset system.
· Check continuity of ground wire.
NOTE: If ground is poor or erratic, shutdowns can occur occasionally even though operation
is normal at the time of checkout.
· Check for excessive heat at igniter or flame rod ceramic base (temperature above 1000˚F
[538˚C] causes short to ground).
If checks are OK, replace ignition module.
NOTE: System failure during a run cycle has a low probability of being the ignition module.
System runs until call
for heat ends.
NO
· Check for proper temperature controller operation.
· Remove valve lead at ignition module. If valve closes, recheck temperature controller and
wiring; if not, replace gas control.
Call for heat ends, system
shuts off.
Troubleshooting ends.
REPEAT PROCEDURE UNTIL TROUBLE-FREE OPERATION IS OBTAINED.
NO
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