Cylindrical motor start capacitor with two terminals, the kind used on compressors and motors

Dual run capacitor (HVAC condenser): testing both sections

A dual capacitor has C (common), HERM (compressor) and FAN terminals with two µF ratings in one can. Test C-HERM and C-FAN separately against the label; one section can fail while the other is fine.

Cross-checked ~20 min moderateBrands: All

Before you start

Pull the disconnect and verify 0 V at the contactor line side
Discharge C-HERM and C-FAN separately and verify 0 V
The compressor terminals and refrigerant circuit are not touched here; sealed-system work is for EPA 608-certified techs only

Diagnostic steps

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

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