Electrical · COMPONENT REFERENCE

Motor run capacitor troubleshooting

Provides the phase-shift function required by applicable PSC fan and single-phase compressor circuits.

Failure causes

Choose a cause for symptoms, checks that separate it from similar faults, repair direction and verification.

Weak or open capacitor →Capacitance outside the specified range reduces the motor circuit's intended phase relationship.Wrong capacitance or terminal wiring →A replacement does not match the required capacitance or its common, fan and compressor connections are misidentified.Shorted or physically damaged capacitor →Internal dielectric damage or a terminal fault creates an abnormal current path.

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.

Fluke: How to measure capacitancePower isolation, discharge and capacitance measurement.

Editorial review: 2026-09-29. Verify the current manual for the installed model.