Specifications

10
XII. TROUBLESHOOTING GUIDE FOR ECM BLOWER
PROBLEM
CHECKS AND CORRECTIONS
Motor rocks slightly
when starting
•This is normal start-up for ECM.
Motor won’t start
•No movement
•Wait for completion of ramp-up at start.
•Check power at motor.
•Check low voltage (24 VAC R to X) at motor.
•Check low voltage connections (G, Y, W2, R, X) at motor.
•Check for unseated pins in connectors on motor harness.
•Test with a temporary jumper between R and G.
•Check motor for a tight shaft.
•Perform Moisture Check*.
Motor rocks, but won’t
start
•Check for loose or compliant motor mount.
•Make sure blower wheel is tight on shaft.
Motor starts, but runs
erratically
•Varies up and down
or intermittent
•Is ductwork attached?
•Check line voltage for variation or “sag”.
•Check low voltage connections (G, Y, W2, R, X) at motor, unseated pins in motor harness connectors.
•Check out system controls, thermostat.
•Perform Moisture Check*.
”Hunts” or “puffs” at
high CFM (speed)
•Does removing panel or filter reduce puffing?
Reduce restriction.
Stays at low CFM
despite call for higher
speed
•Check low voltage wires and connections.
•Verify fan is not in delay mode; wait until delay complete.
•”R” missing/not connected at motor.
Stays at high CFM
•Verify fan is not in delay mode; wait until delay complete.
•”R” missing/not connected at motor.
Blower won’t change
CFM after adjusting
the speed control
setting.
•Power to the unit must be reset to enable the new settings.
•Verify fan is not in delay mode; wait until delay complete.
•”R” missing/not connected at motor.
Blower won’t shut off
•Current leakage from controls into G, Y, or W?
Excessive noise
•Determine if it’s air noise, cabinet, duct or motor noise.
Air noise
•High static creating high blower speed?
- Does removing filter cause blower to slow down? Check filter.
- Use low-pressure drop filter.
Check/correct duct restrictions.
Noisy blower or
cabinet
•Check for loose blower housing, panels, etc.
•High static creating high blower speed?
- Check for air whistling through seams in ducts, cabinets, or panels.
Check for cabinet/duct deformation.
*Moisture Check
•Connectors are oriented as recommended by equipment manufacturer?
•Is condensate drain plugged?
•Check for low airflow (too much latent capacity)
•Check for undercharged conditions.
•Check and plug leaks in return ducts, cabinet.
**Comfort Check
•Check proper airflow settings.
•Low static pressure for low noise.
•Set low continuous-fan CFM .
•Thermostat in good location?