Emerson 50A55 - Manual

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259

TECHNICAL HELPTECHNICAL HELP

INTEGRATED FURNACE

CONTROL MODULE

TROUBLESHOOTING

GUIDE

50A55 INTEGRATED FURNACE CONTROL MODULE

Qualified Serviceman’s Troubleshooting Guide

TROUBLESHOOTING PROCEDURE

If the light on the module is on continuously, the fault is likely to be internal to the

module. To make sure, interrupt line or 24 volt thermostat power for a few seconds

and then restore. If internal fault is indicated again, and flame sensor is not shorted

to ground, replace control. A flashing light indicates the problem is most likely in the

external components or wiring. Proceed as follows:

WARNING

!

Failure to read and follow all
instructions carefully before in-
stalling or operating this control,
could cause personal injury and/
or property damage.

WARNING

!

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.

The following steps must be performed first before any troubleshooting begins.

) Disconnect electric power to system at main fuse or circuit breaker.

2) Visually inspect equipment for apparent damage. Check wiring for loose

connections.

3) Check for proper grounding and reversed polarity.

A. Check continuity for C terminal on module to electrical service ground and

connection at the furnace junction box. If ground connection is open, check

module ground connection and the electrical service ground connection.

Repair and retest.

B. Re-connect electric power to system.

C. Check for voltage between the line neutral terminal and furnace ground. 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. Recheck system for proper operation.
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

equipment or 50A55-XX modules found on Lennox equipment.

FAULT INDEX CHART

No manual fan ............................................ A - K
Power supply and voltage .......................... C - G
No fan at cooling speed .............................. 2A - 2L
No induced draft motor ............................... 3A - 3H

LED flashing 2X without inducer

................. 3E

LED flashing 3X with inducer

...................... 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
Polarity check ............................................. 5L - 5M
Ignitor stays on after burner ignition ........... 5B - 5C