What happens
A motor winding, internal protector or applicable electronic drive fails to produce rotation.
Typical symptoms
Compressor operates but the fan is stopped, hums or repeatedly cuts out.
Checks that distinguish this cause
Verify command and power using the specific motor procedure. For a PSC motor, isolate the winding and capacitor tests; for ECM, use its module and signal diagnostic instructions.
What can look similar
A failed capacitor, broken lead or blocked blade can stop a healthy motor.
Repair direction
Replace the confirmed failed approved motor or module and correct airflow or mechanical stress.
Verify the repair
Confirm direction, blade clearance and stable fan operation with the compressor.
Equipment-specific limits
Identify PSC, ECM or other motor technology and rotation requirements. Keep clear of automatic starts and moving blades.
Practice this diagnosis
These simulated calls exercise this component or repair family. The article describes a broader diagnostic process; a call may represent a different cause within that family.
References and applicability
Original HVACSim explanations with manufacturer and instrument-maker references for further reading. These resources support the subject; their model-specific examples are not specifications for every system.
- Copeland: CoreSense diagnostics for scroll air-conditioning compressors (AE8-1379)Model-specific diagnostic examples; flash codes are not universal.
- Fluke: How to measure capacitancePower isolation, discharge and capacitance measurement.
Editorial review: 2026-09-29. Verify the current manual for the installed model.