General Guidelines To Troubleshooting Ge Ecm - Thermo Pride OH5-85DE Operation Manual

All installations and services must be performed by qualified service personnel.
The red Board Status LED has two functions:
It will light when the board recognizes a valid input signal and will stay lit until all valid signals are removed.
This is intended to show that the board is functioning and able to respond to input signals.
It will flash rapidly while120VAC is missing from the LIMIT switch. This is intended to give a quick visual
indication of the High LIMIT switch.
B. GENERAL GUIDELINES TO TROUBLESHOOTING GE ECM – DRIVEN SYSTEMS
:
Disconnect power from unit before removing or replacing connectors, or servicing motor.
Wait at least 5 minutes after disconnecting power before opening motor.
SYMPTOM
Motor rocks slightly when starting
Motor won't start
 No movement
 Motor rocks, but won't start
Motor oscillates up & down while being tested off
of blower
Motor starts, but runs erratically
 Varies up and down or intermittent
"Hunts" or "puffs" at high CFM (speed)

Stays at low CFM despite system call for cool or

heat CFM
 Stays at high CFM
 Blower won't shut off
CAUSE/PROCEDURE
 This is normal start-up for ECM
Check power at motor

Check low voltage (24 VAC R to C) at motor

Check low voltage connections

(G,PWM,W,R,C,) at motor
 Check for unseated pins in connectors on motor
harness
 Test with a temporary jumper between R – G
 Check motor for tight shaft
 Perform motor/control replacement check
 Run Moisture Check
 Check for loose or compliant motor mount
 Make sure blower wheel is tight on shaft
 Perform motor/control replacement check
 It is normal for motor to oscillate with no load on
shaft.
 Check line voltage for variation or "sag"
 Check low voltage connections
(G,PWM,W,R,C,) at motor, unseated pins in
motor harness connectors
Check "Bk" for erratic CFM command (in

variable speed applications)
Check-out system controls – T'stat?

Perform Moisture Check

Does removing panel or filter reduce "puffing"?

 Reduce restriction
 Reduce max airflow
Check low voltage (T'stat) wires and connections

Verify fan is not in delay mode – wait until delay

complete
 "R" missing/not connected at motor
 Perform motor/control replacement check
 "R" missing/not connected at motor
 Is fan in delay mode? – wait until delay time
complete
 Perform motor/control replacement check
 Current leakage from controls into G,Y or W?
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