Troubleshooting Chart
FOR MODELS: 3508331; 3508332; 5508331; 5508332
SYMPTOM
1. Nospark-- nopilotgas.
2. Spark -- but no pilot gas,
3. Pil_gas--but no spark.
POSSIBLE CAUSE(S)
a. No main powe_
b. Faulty transformer.
c. Faulty thermostat.
d. Faulty limit switch.
e. Faulty ignitioncontrol.
f. Faulty wiring.
g. Vent safety shutoffdevice.
a. Faulty ignition.
b. No gas supplied to pilot valve.
c. Manual valves in OFF position.
d. Faulty pilot valve.
e. Faulty wiring.
f. Restricted pilot line or clogged
pilot orifice.
a. Faulty ignitioncontrol.
b. Broken or shorted electrode
assembly.
CORRECTIVE ACTION
a.-e. Performnormalsystemchecks of main power,transformer,ther-
mostat, limit switch, and replace faulty component.
With power ON, turnthermostatto the lowestsetting, wait 10
seconds and return to HIGH setting. With power ON and ther-
mostatset at its highest position, setvoltmeterto 24V scale and
attach probes to terminals "TR" and "TH" on the ignition con-
trol unit.
If you read 24V and there still is no sparkor pilot gas, the igni-
tion controlis defective and must be replaced.
f. Test wiring. Repair or replace.
g. Check wiring connectionsfromvalve tovent safetyshutoffdevice,
be sure all connectionsare tight. Check for blocked vent.
a. See le.
b. Check for availabilityof gas atgascontrol. Makesure the manual
valve (gas cock) on the gas control are in the full ON position.
No pilot gas could be caused by a plugged pilot tubing. Also
check the pilot adjustment at the gas control.
c. See 2b.
d. See 2b.
e. See lf.
f. See 2b.
a.
With power ON, turn thermostat to the lowest setting, wait 10
secondsand return1ohighsetting Withpower ONand thermostat
set at its highest position, set voltmeter to 24V scale and attach
probes to terminals"24V" (*TH) and "GRD" ('TR) on the igni-
tion control unit. If you read 24V and there is still no spark or
pilotgas, the ignition control is detective and must be replaced.
With thermostat turned to its highest setting, set test meter to
24Vscale.Touchprobes to "PV/MV" and "PV" terminals on Gas
Valve. If you do not get a 24V reading, check wiring. If wiring
tests okay, check ignition control.
Connectprobesto "PV/MV" AND"PV" terminals onignitioncon-
trol. If youdo not read24V,the ignition control must be replaced.
Remove wire at "PV/MV" terminal at the ignition control, being
careful not to touch any metal parts; disconnect the electrode
wire at the ignition control. Connect one end of a jumper wire
to terminal "GND" (DO NOT REMOVE EXISTING WIRE.) At-
tach the other end of the jumper wire to the metal blade of a smal!
screwdriver. Position end of metal blade approx. 1/8" from ter-
minal. Reconnect "PV/MV" terminal Sparking should occur be-
tween screwdriver blade and terminal
If no sparking occurs, the ignition control must be replaced.
Checkthe pilot and electrode assemblyfor proper electrodegap
(3/32" to 1/8") or any possible shorting of electrode 1osurroun-
ding metal surfaces. Make sure the spark ignitor and electrode
connectionsto the ignition control are tight. The ignition control
and pilot burner musl both be chassis ground. If there is still no
spark, the pilot and electrode assembly must be replaced.
(continuednextpage)
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