5 Signs Your AC Contactor Needs Replacement

What the Contactor Does

The contactor is an electrically controlled switch that turns your compressor and condenser fan on and off when the thermostat calls for cooling.

Signs of a Failing Contactor

1. Chattering or humming: Weak coil or dirty contacts
2. AC won't turn on: Contactor not pulling in
3. AC won't turn off: Welded or stuck contacts
4. Visible pitting or burn marks: Contacts are worn
5. Intermittent operation: Poor contact connection

Testing the Contactor

1. Turn off power to the unit
2. Check for 24V at coil terminals during call for cooling
3. Measure coil resistance (typically 10-20 ohms)
4. Inspect contacts for pitting or discoloration