Service manual

SECTION 13: TROUBLESHOOTING
51
13.1 Troubleshooting Flow Chart
Check wiring between
the power cord, blower
motor and transformer.
No
Replace ignition module.
Replace pressure switch.
Reconnect transformer
wires. Place a jumper wire
across each pressure switch.
Is there a spark?
Ye s
No
Replace transformer.
Remove the blue and yellow
wires from the transformer.
Is there 24 V at the
transformer secondary?
No
Ye s
Is the voltage
at the transformer black
and white leads 120 V?
Ye s
Repair, replace or tighten
hoses as necessary.
Are the air hoses to the
pressure switches secure
and leak free?
No
Ye s
Carefully reset the
spark gap to 1/8" (3 mm).
Replace igniters and
ignition wires as needed.
Remove
obstruction.
Is the vent pipe or the inlet
of the burner obstructed?
Ye s
No
Are the igniter gaps
set at 1/8" (3 mm)?
Ye s
No
Unplug burner and check
igniters and ignition wires.
Are they damaged?
No
Ye s
Is there spark
at the igniters?
No
Blower bearings may
have failed.
Replace blower.
Replace blower.
Check relay wiring
(if applicable) and wiring
to the burner.
Check thermostat wiring
and replace thermostat if
necessary.
Is the blower
obstructed?
No
Remove
obstruction.
Ye s
Unplug blower. Does
the blower turn freely?
No
Ye s
Is there power (120 V) at
the burner?
Ye s
No
Place a jumper across the
thermostat terminals.
Does the blower turn on?
No
Ye s
Turn up thermostat.
Does the blower turn on?
No
Ye s