Skip the auto shop - Our mechanics make house calls

Q: What could be causing my AC to intermittently blow hot air?

asked by on

My AC suddenly started to blow hot air while driving yesterday. It would work fine as I was driving, but if I was stopped at a stop light for any length of time, it would start to blow hot air as soon as I started driving again. I replaced my battery and serpentine belt 4 years ago, and my cabin filter was replaced a year ago. Would any of these be linked to the AC acting up?

My car has 50075 miles.

The most common problem for this is usually a cooling fan that is not coming on with the A/C. Another possibility is that the A/C is low on refrigerant and may have a leak at the compressor or lines to the compressor.

I recommend having the A/C diagnosed to test for any of these problems and go from there. The A/C filter only filters out dirt like a house air filter does. Not changing it will reduce air flow but not change the temperature.

The battery and belts would not be at fault unless they are bad again, you should have them checked when you have the A/C pressures looked at, just to be sure.

I’d recommend getting some help from a certified technician for this job. They will be able to perform the necessary checks to diagnose your A/C issue and fix it accordingly.

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: hissing or air noise when i press gas

You may need to check your air cleaner or intake tube for loose or cracked tubes, or the air filter housing might not be seated correctly. Try to duplicate the noise by manual operation of the throttle while you have...

Q: Air conditioning not working on my truck

When I looked up your vehicle I see many recalls that may pertain to your model but none are for the A/C system. I would contact your dealer for the possible safety recalls for that vehicle. The A/C system, if...

Q: My Check Engine Light turns on and off, and the Service Traction Light is on

There are several components that can cause these types of symptoms. Issues that cause poor performance and shaking can be fuel, air, spark, electronic, or mechanical problems. The good news is that the Check Engine Light has come on. This...

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...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...