What happens
The motor protector interrupts operation because of heat or an abnormal operating condition.
Typical symptoms
Compressor stops while hot and may resume after cooling; an apparent open winding can be temporary.
Checks that distinguish this cause
Review history and OEM reset behavior. Investigate start components, supply, condenser airflow and refrigerant operating conditions before treating a reset as a repair.
What can look similar
A permanently open winding remains a separate possibility. Outdoor fan operation does not prove the compressor has acceptable conditions.
Repair direction
Correct the reason for overheating; allow only the documented reset process without bypassing the protector.
Verify the repair
Verify sustained operation through the condition that previously caused a trip.
Equipment-specific limits
Single-phase C/R/S checks do not apply to every inverter or three-phase compressor. Use model data, isolate electronics as directed and never run or perform insulation tests under vacuum.
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.
- Copeland: Refrigeration basics: troubleshooting fundamentalsCompressor and refrigerant troubleshooting concepts, not a charging specification.
- Copeland: Compressor terminal venting safetyStop conditions and hazards around compressor electrical terminals.
- Fluke: Insulation resistance and electrical testing for HVAC compressor motorsInsulation-testing precautions, including avoiding tests under vacuum; use compressor-specific instructions.
Editorial review: 2026-09-29. Verify the current manual for the installed model.