Why does my car AC stop working when it's really hot outside?
The air conditioning compressor repeatedly clicks on and off without cooling when ambient temperatures exceed extreme heat thresholds. This thermal overload prevents the system from maintaining cold airflow during peak heatwaves.
What the numbers show
Counted from the threads quoted below. How we count
- This comes up 11.6× more often in r/MechanicAdvice than across the site as a whole.
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.
- 1Check for a clogged cabin air filterDid this help you?
- 2Check for a clogged AC drainDid this help you?
- 3Recharge the refrigerant systemDid this help you?
- 4Check refrigerant chargeDid this help you?
- 5Verify cooling fans are workingDid this help you?
- 6hitting the blower motor to make it kick back onDid this help you?
- 7disconnecting the battery to clear computer glitchesDid this help you?
- 8trying to use a refrigerant recharge canDid this help you?
- 9Having the freon checked, vacuumed, filled, and leak-testedDid this help you?
- 10Relying on suggestions from friends and family for potential parts to replaceDid this help you?
- 11Changing the blower motor, fuses, and relaysDid this help you?
- 12Adding freonDid this help you?
- 13Tapping the blend door actuator under the dash to free it upDid 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.
“I've been dealing with a hot AC for about a month now and I'm out of ideas. Could I get some suggestions?”source ↗
“We just bought a house so money is insanely tight right now, and the timing couldn't be worse.”source ↗
“Why my car's AC blows cold at 86°F but fails completely at 100°F? the AC compressor clicking on and off every few seconds when is 100+ but is not working (ford fusion 2013)”source ↗
“In my 2017 Highlander the front AC went out in my Highlander. The rear AC still works perfectly fine.”source ↗
“Any other ideas on why the AC does not blow in the front?”source ↗
“Mechanics of Reddit I need your advice I have a 2012 Hyundai Accent Gls 4 cylinder with. 1.6L engine and here recently my a/c has not been working right it blows hot during the day and in south Louisiana it has been very heat in the summer and fall months however at night it blows cool to cold like it should.”source ↗
“I need to add advice on the situation before spending a bunch of money and time on fixing the problem that just might be a simple fix and court way less time and money.”source ↗
“Why my car's AC blows cold at 86°F but fails completely at 100°F? the AC compressor clicking on and off every few seconds when is 100+ but is not working (ford fusion 2013)”source ↗
Where this came up
People with this problem also raised
- 3How to cool down a house when the AC breaks during a heatwave
- 5Why does my AC stop working at night?
- 23Why does my car engine cut out after driving for a while?
- 2Why is my brand new AC condenser fan not spinning?
- 12Car heater blowing cold air even with good coolant and thermostat
- 10Why does my car overheat only when idling?