29
YES
NO
YES
YES
YES
YES
NO
NO
YES
Pull ignition lead and
check spark at module.
NOTE:
Before troubleshooting, familiarize yourself with the startup and check
procedure.
Check line voltage power, low voltage transformer, limit controller, thermostat
(controller) and wiring. Also, check air proving switch on combustion air
blower system (if used) and that vent damper (if used) is open and end switch
is made.
Spark Across Igniter/Sensor Gap.
Spark okay?
Turn gas supply OFF. Turn thermostat
(controller) to call for heat.
Power to module (24V module)
On models with vent damper
plug, make sure vent damper
has not been installed, then
removed. Replace vent damper
if necessary.
On other models, replace module.
NO
YES
Turn gas supply ON.
Pilot Burner Lights?
Check ignition cable, ground wiring, ceramic insulator and gap, and correct.
Check boot of the ignition cable for signs of melting or bucking. Take
protective action to shield cable and boot from excessive temperatures.
Check that all manual gas valves are open, supply tubing and pressures are
good, and pilot burner orifi ce is not blocked.
Check electrical connection between module and pilot operator on gas control.
Check for 24 Vac across PV-MV/PV terminals on module. If voltage is
okay, replace gas control: if not, replace module.
NOTE:
If the control, goes into lockout, reset system.
Spark Stops When Pilot Lit?
Check continuity of ignition cable and ground wire.
Clean fl ame rod.
Check electrical connections between fl ame rod and module.
Check for cracked ceramic fl ame rod insulator.
Check that pilot fl ame covers fl ame rod and is steady and blue.
Adjust pilot fl ame.
If problem persists, replace module.
NO
Main Burner Lights?
NO
YES
Check continuity of ignition cable and ground wire.
NOTE
: If ground is poor or erratic, shutdowns may occur occasionally even though
operation is normal at the time of checkout.
Check that pilot fl ame covers fl ame rod and is steady and blue.
If checks okay, replace module.
Check for 24 Vac across MV-MV/PV terminals. If no voltage, replace module.
Check electrical connections between module and gas control. If okay,
replace gas control or gas control operator.
NOTE:
If the control, goes into lockout, reset system.
System Runs Until Call For Heat
Ends.
NO
Call For Heat Ends
NO
System Shuts OFF?
Troubleshooting Ends.
Check for proper thermostat (controller) operation.
Remove MV lead at module: if valve closes, recheck temperature controller
and wiring: if not, replace gas control.
Repeat procedure until trouble free operation is obtained.
NO
PILOT SYSTEM TROUBLESHOOTING TABLE
