Video · AC Repair and Troubleshooting
AC Contactor Replaced Early: What a Pitted One Looks Like
An AC contactor is the switch that sends power to the outdoor unit when the thermostat calls for cooling. Once its contacts pit and burn, it can take out fuses, the transformer and the control board.
Job footageSwiftPro
- Topic
- AC Repair and Troubleshooting
- Length
- 0:34
- Posted
- September 15, 2026
- Shot by
- The SwiftPro crew, Northern Virginia
What you’re seeing in this video
A young SwiftPro tech stands beside a brick house holding a new contactor, the relay that closes to power the compressor and outdoor fan. He's replacing the old one before it fails rather than waiting for a no-cool call.
The camera then moves inside the outdoor unit for a close-up of the worn contactor and its wiring. On a pitted contactor the contact points are scarred and blackened from years of arcing every time the AC cycles on and off. He explains that a contactor in that shape can cause shorts back at the board, blow fuses or take out the transformer.
Hey guys, I'm running with SwiftPro. Today we're changing out a contactor. As you guys can see here, ain't she nice and pretty? We're replacing this guy right here.
So, here is the pitted contactor. We're replacing it proactively because we're trying to prevent any other issues from happening later on down the road. Issues that it can cause are shortages down back at the board, fuses, and or the transformer. And that could cost you guys a lot of money later down the road.
And it could save you a lot of time and headaches for future repairs.
Why it matters in your house
- A buzzing or chattering outdoor unit, or one that won't shut off when the house is cool, are classic bad AC contactor symptoms. A stuck contactor can run the compressor nonstop.
- Contacts that pit unevenly can starve the compressor of full voltage, which makes it run hotter and shortens its life. An inexpensive part is protecting an expensive one.
- During a tune-up a tech should look at the contactor's points, not just confirm the AC turns on. Scorched contacts are an easy catch before summer.
How do I know if my AC contactor is bad?
The outdoor unit may hum or buzz without starting, chatter on and off, or keep running after the house is cool. Some contactors fail closed, so the fan and compressor never stop. A tech confirms it by checking the contact points and the voltage across them, and a pitted contactor is a quick swap.
Want it done at your place? See AC Repair and Troubleshooting at SwiftPro or call (703) 997-9757.
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