Comfortmaker Failed Start/Run Capacitor or Locked Compressor

Comfortmaker outdoor unit makes a loud buzzing or humming sound, but the fan and compressor do not start.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Open or weak dual run capacitor, Locked rotor on the compressor, Faulty contactor not delivering full voltage.

Safety: Turn off power at the disconnect and verify with a meter. Capacitors can hold a charge; discharge safely before handling.

Steps:

Inspect capacitor: Look for a bulging top, oil leakage, or rust. Replace if any signs of failure.
Test capacitance: Remove wires and test with a capacitance meter. Replace if more than ±10% off the rating.
Check contactor: Ensure contacts are clean and making a good connection.
Attempt restart: After replacing the capacitor, restore power and test.

Note: If the compressor still only hums and trips the breaker, it may be locked and require professional evaluation.

Medium 3/5

Dual Run Capacitor

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