Supco Compressor Contactor
Reliable 2-pole contactor for AC compressor control.
Overview
A 2-pole 24-volt contactor from Supco for controlling the compressor and condenser fan in residential AC units and heat pumps. The contactor is the relay that sends power to the compressor when the thermostat calls for cooling. When it fails, symptoms include the condenser fan running but compressor not engaging, or a chattering sound from the electrical panel.
+ Pros
- 2-pole 30-amp rating covers most residential compressors
- 24V coil voltage matches standard thermostat control circuits
- Affordable replacement — one of the cheapest AC repairs
- Simple installation — two screws and four wires, documented here
− Cons
- Coil resistance varies — verify your system's coil spec matches
- Some units use 3-pole contactors — verify before ordering
- Cheap contactors may have shorter lifespan than OEM units
Who It's For
Homeowners whose condenser fan runs but compressor doesn't click in, or who hear a buzzing/chattering from the contactor. If you can hear the thermostat call for cooling but the contactor doesn't pull in, the 24V coil may have failed.
Who Should Skip This
If the compressor and fan both don't run, check for main power (breaker, disconnect, high-pressure switch). A bad contactor would still show the fan sometimes running. Also skip if you haven't ruled out a bad capacitor — that's 4x more common.
Compatibility
Most residential AC units and heat pumps with 2-pole, 24V coil contactor systems
Bottom Line
At under $20, a contactor replacement is the cheapest AC repair you can do. If the contactor is chattering or pitted, replace it. Keep a spare if you live in a hot climate — contactors fail more on peak cooling days.
Pricing and availability may change. Check current price before purchasing.
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