Skip the auto shop - Our mechanics make house calls

Q: A/C intermintent blows hot air.

asked by on

Starts out blowing cold and some time later starts blowing hot air. Acts like the blend doors are getting changed for some reason. Diags show no fault codes.

My car has 150000 miles.
My car has an automatic transmission.

A: Sometimes the A/C cycling switch will cycle...

Sometimes the A/C cycling switch will cycle the A/C off like it should when the temperature reaches cycling pressures of about 24 psi. Once it cycles off and the pressures rise to the set pressure to cycle back on, it does not cycle back on and the A/C starts getting warm. The intermittent low pressure cycling switch is the most common cause of this problem and should be verified to be the problem by a qualified mechanic. Replace the cycling switch and retest the system to be cycling on and off correctly. If you need help getting this checked, have a certified professional from YourMechanic come to your location to inspect the AC system and move forward with the appropriate repair.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Air conditioner leaking water

Hi there. The air conditioning system will acquire condensation during operation. To prevent the condensation from spilling into the vehicle, there is a drain equipped. While the vehicle is running and the air conditioning system activated, it is normal for...

Q: Steering wheel is tightening up when I try to turn it to the left.

Sounds like you might be having an issue with the rack and pinion. There are valves that direct hydraulic fluid pressure to the appropriate side of the rack to help you steer. If one of those valves malfunctions, a problem...

Q: My car is overheating quickly - 2000 Lincoln LS

Hi and thanks for contacting YourMechanic. Check to see if the electric fan is coming on when at idle. If the fan is not coming on, check the fuse box for any blown fuses. If all of the fuses are...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.