Possible Cause: Compressor is not being called.
Corrective Action: Verify controller or thermostat is calling for compressor operation.
Possible Cause: Electrical power issue.
Corrective Action: Verify power to the unit and to the compressor contactor matches nameplate. For three phased units, verify unit is not single-phasing.
Possible Cause: Control circuit is open.
Corrective Action: Verify 24VAC to compressor contactor holding coil. Trace out 24VAC power and determine where signal is lost if contactor does not pull in. Replace any defective components.
Possible Cause: Internal overload is tripped.
Corrective Action: Turn off power and allow compressor to cool to reset overload.
Possible Cause: Compressor locked out on alarm.
Corrective Action: For controllers: clear alarm and reset system enable to AUTO. For thermostat/control by others, pressure alarms require power to be cycled.
Possible Cause: Digital scroll control board lockout.
Corrective Action: Refer to the digital scroll LED troubleshooting documentation on unit and diagnose via LED sequence.
Possible Cause: Motor has shorted or grounded.
Corrective Action: Ohm out compressor motor. Replace compressor if defective.