Why does my car A/C compressor keep turning on and off?
An air conditioning compressor that repeatedly spins, catches, and stops causes low airflow for both cooling and heating. This short cycling prevents the system from maintaining stable pressures, leaving drivers frustrated by a lack of proper cabin climate control.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Replacing the vacuum hose going into the vacuum chamber
- 2Replacing the PCV valve
- 3Checking refrigerant and freon levels
- 4Testing sensors or hooking up a manifold gauge set
- 5Adding dye to the system to inspect for leaks
- 6Spraying soapy water on valves and connections to look for leaks
- 7Using an electronic leak detector or UV glasses and light
- 8Replacing relays multiple times
- 9Replacing the high-side pressure switch
- 10Using a scan tool to check live sensor data
- 11Checking wiring against the wiring diagram
- 12Posting pictures of the wiring for review
- 13Setting the thermostat to an artificially low temperature to force the compressor to run continuously.
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“This gear/module will spin, catch and stop, then start up again. Is this normal, or is there an underlying issue I'm not seeing?”source ↗
“Changed it to a new one with the same specs and now the fan is running and restarting every few seconds and still not blowing cold air indoor”source ↗
“If my guess is correct I must have wired it incorrectly and and I can rewire it. Although I am pretty sure I wired it exactly how the old capacitor was wired.”source ↗
“Because I have little air flow in both my a/c and heat, that's why I'm trying to fix it”source ↗
“My new compressor is now short cycling and the pressures I get are 20-25psi low side and 150-175psi on the high side at 85F ambient temp.”source ↗
“Does anyone know what could possibly be causing this? About to shoot the damn truck”source ↗
“Any way to fix a/c compressor don't stop ? Replace 3 time my relay. 3 time the presostat. (Sensor on the high side)”source ↗
“I have a 5,000 BTU window AC in a slightly larger room than its rated 150 sq. ft. I set it to 60°F, but the compressor shuts off when the room is around 68°F. I’m also not seeing much (or any) water draining outside.”source ↗
“What’s confusing is that I’ve purchased two other window ACs in the past, and both did the exact same thing they would shut the compressor off before reaching the set temperature.”source ↗
“I’m setting it to 60°F because I want the AC to keep running continuously. That way, I can manually turn it off when I want rather than having it shut off on its own before the room reaches the temperature I’m trying to maintain.”source ↗