INTEGRATED FURNACE
CONTROL MODULE
TROUBLESHOOTING
GUIDE
50A55 INTEGRATED FURNACE CONTROL MODULE
QualiedServiceman’sTroubleshootingGuide
TROUBLESHOOTING PROCEDURE
Ifthelightonthemoduleisoncontinuously,thefaultislikelytobeinternaltothe
module.Tomakesure,interruptlineor24voltthermostatpowerforafewseconds
andthenrestore.Ifinternalfaultisindicatedagain,andamesensorisnotshorted
toground,replacecontrol.Aashinglightindicatestheproblemismostlikelyinthe
external components or wiring. Proceed as follows:
Failure to read and follow all
instructions carefully before in-
stalling or operating this control,
could cause personal injury and/
or property damage.
Turn power off before any troubleshooting or servicing begins.
Line voltage (120 VAC) could be present on the surface of the ignitor, if the sys-
tem is not correctly wired. Such voltage can cause serious injury or death.
Thefollowingstepsmustbeperformedrstbeforeanytroubleshootingbegins.
1)Disconnectelectricpowertosystematmainfuseorcircuitbreaker.
2)Visuallyinspectequipmentforapparentdamage.Checkwiringforloose
connections.
3)Checkforpropergroundingandreversedpolarity.
A. CheckcontinuityforCterminalonmoduletoelectricalservicegroundand
connectionatthefurnacejunctionbox.Ifgroundconnectionisopen,check
module ground connection and the electrical service ground connection.
Repair and retest.
B. Re-connect electric power to system.
C. Checkforvoltagebetweenthelineneutralterminalandfurnaceground.If
voltage exists, the main power supply lines are improperly connected to the
furnace (REVERSED POLARITY). Again disconnect electric power to system;
then reverse incoming supply leads to furnace. Repeat step.
D. Rechecksystemforproperoperation.
If neither apparent damage, loose connection nor reversed polarity is the problem,
proceed to troubleshooting chart or fault index chart that is suggested by the actual
condition.
NOTE: This troubleshooting guide is not for 50A55-4XX modules found on Trane
equipmentor50A55-1XXmodulesfoundonLennoxequipment.
FAULT INDEX CHART
No manual fan ............................................ 1A - 1K
Power supply and voltage .......................... 1C - 1G
No fan at cooling speed .............................. 2A - 2L
No induced draft motor ............................... 3A - 3H
LEDashing2Xwithoutinducer................. 3E
LEDashing3Xwithinducer...................... 3I - 3O
Ignitor does not glow .................................. 4A - 4D
Burner does not stay lit ............................... 4E - 4N
Gas supply problem.................................... 4F - 4K
No outlet pressure ...................................... 4H - 4J
Gas valve does not energize ...................... 4L - 4N
Flame sensor fault ...................................... 5A - 5P
Burner ground............................................. 5K
Polaritycheck ............................................. 5L - 5M
Ignitor stays on after burner ignition ........... 5B - 5C
TECHNICAL HELP
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