44
Is the spark
igniter sparking?
NO
Check continuity of the spark
cable. Check for 24VAC on
the TH terminal (gray wire) on
the ignition module.
Is the pilot
staying ON?
STEP 1:
STEP 2:
Check the pilot
tube for gas.
Check for draft.
NO
NO
YES
Replace ignition
module.
Is there 24 VAC (purple
wire) on the 4-pin
connector plug on the
temperature controller?
YES
Is there 24VAC
(tan wire) on the
4-pin connector
plug on the
temperature
controller?
NO
Check for an open
sensor. If not open,
replace temperature
controller.
Is the gas valve
getting 24VAC?
STEP 3:
Replace ignition
module.
NO
YES
Check X and B on the
terminal strip if the flow
switch is installed. Check
for an open auto reset high
limit.
Check vent damper, 3-pin
louver relay connectors, and
venter proving.
Check 24VAC at R and W on
the (EMS) terminal strip.
NO
Check the vent damper or
the vent damper plug and
the voltage to and from the
transformer.
YES
Check all safety limit devices.
Check 4-pin low water cutoff
connector.
YES
YES
NO
TROUBLESHOOTING GUIDE
45,000 - 500,000 Btu/hr Models - Boilers & Water Heaters F9/M9