Why does my outside AC unit keep running when turned off?
When an outdoor unit continues running despite being turned off at the thermostat, a failed or stuck contactor is usually to blame. Because power remains bridged, the only way to stop the system is by manually flipping the exterior switch or breaker.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1turning off the main breaker or outside switchDid this help you?
- 2Pulling the RAP (Retained Accessory Power) fuse or relay manuallyDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“The outside unit fan and compressor continuously runs even when the thermostat is turned off.”source ↗
“The only way to stop it is to turn the breaker or switch outside off.”source ↗
“This is the first time I’ve ever looked at this, so basically this contactor is done for?”source ↗
“This car is retaining power to instrument cluster, radio, and windows after being shut off no matter what door is opened. Pulled RAP + replaced ignition switch with no change. Not sure where to go from here. Any advice on where to start looking for trouble is appreciated.”source ↗
“I have a 1985 ford f150 300inline 6 yfa carb, it disels pretty heavy after I turn it off and sometimes an occasional "shwoosh" noise.”source ↗
“Happens more and worse after a longer drive say 20-30 minutes, verses just a 5 minute test drive.”source ↗
“I replaced spark plugs, sealed all the know vacuum leaks, and put some techron cleaner to help with carbon buildup, anyone else have any advice on what it could be?”source ↗