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SECTION 12: TROUBLESHOOTING
51 of 59
12.1 Troubleshooting Flow Chart
Replace pressure switchYES
NO
Replace transformer.
YES
NO
Remove obstruction.YES
NO
YES
NO
Replace blower.
NO
YES
NO
YESNO
YES
YES
NO
NO
YES
Is there spark at the igniter?
YES
NO
NO Is the blower obstructed?
Remove obstruction.
NO
NO
YES
Replace ignition module.
With the blue and yellow
wires still removed, is the
voltage at the transformer
black and white leads 120 V?
YES
Is there power 120 V at
the burner?
Turn up thermostat.
Does the blower turn on?
Remove the blue and yellow
wires from the transformer.
Is there 24 V at the
transformer secondary?
Reconnect transformer
wires. Place a jumper wire
across the pressure switch.
Is there a spark?
Check wiring between the
power cord, blower motor
and transformer.
Replace igniter and
ignition wire as needed.
Carefully reset spark gap
to 1/8"
Are the air hoses to the
pressure switch secure and
leak free?
Repair, replace, or tighten
hoses as necessary.
Is the vent pipe or the inlet of
the burner obstructed?
Is the igniter gap
set at 1/8"?
Unplug burner and check
igniter and ignition wire. Are
they damaged?
Blower bearings may have
failed. Replace blower.
Check relay wiring
(if applicable) and wiring
to the burner.
Check thermostat wiring
and replace thermostat if
necessary.
Place a jumper across the
thermostat terminals.
Does the blower turn on?
Unplug burner. Does the
blower turn freely?