SERVICING
105
Symptoms of
Abnormal Operation
Fault Description(s) Possible Causes Corrective Action
Cautions and
Notes
- Motor rocks slightly
when starting.
- This is normal start-up
for
variable speed motor.
---- ---- ----
- No movement.
- Manual disconnect switch off or door
switch open.
- Blown fuse or circuit breaker.
- 24 Vac wires miswired.
- Unseated pins in wiring harness
connectors.
- Bad motor/control module.
- Moisture present in motor or control
module.
- Check 115 Vac power at motor.
- Check low voltage (24 Vac R to C) at motor.
- Check low voltage connections
(G, Y, W, R, C) at motor.
- Check for unseated pins in connectors
on motor harness.
- Test with a temporary jumper
between R - G.
- Turn power OFF prior to repair.
Wait 5 minutes after disconnecting
power before opening motor.
- Handle electronic motor/control
with care.
- Motor rocks,
but won't start.
- Loose motor mount.
- Blower wheel not tight on motor shaft.
- Bad motor/control module.
- Check for loose motor mount.
- Make sure blower wheel is tight on shaft.
- Perform motor/control replacement
check, ICM-2 motors only.
- Turn power OFF prior to repair. Wait 5
minutes after disconnecting power
before opening motor.
- Handle electronic motor/control
with care.
- Motor oscillates up
& down while
being tested off of
blower.
- It is normal for motor
to oscillate with no
load on shaft.
---- ---- ----
- Varies up and down or
intermittent.
- Variation in 115 Vac to motor.
- Unseated pins in wiring harness
connectors.
- Erratic CFM command from "BK"
terminal.
- Improper thermostat connection
or setting.
- Moisture present in motor/control
module.
- Check line voltage for variation or "sag".
- Check low voltage connections
(G, Y, W, R, C) at motor, unseated pins in
motor harness connectors.
- Check-out system controls - Thermostat.
- Perform Moisture Check.*
- Turn power OFF prior to repair.
- "Hunts" or "puffs" at
high CFM (speed).
- Incorrect or dirty filter(s).
- Incorrect supply or return ductwork.
- Incorrect blower speed setting.
- Does removing panel or filter reduce "puffing"?
- Check/replace filter.
- Check/correct duct restrictions.
- Adjust to correct blower speed setting.
- Turn power OFF prior to repair.
Troubleshooting Chart for ECM/ICM Variable Speed Air Circulator Blower Motors
- Motor won't start.
- Motor starts, but runs
erratically.
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