Skip the auto shop - Our mechanics make house calls

Q: AC works fine during driving, blows warm when idling

asked by on

Hi. The air conditioning in my car is not working correctly. It works fine when I drive the car. However, it starts blowing warm air when I decelerate, like during idling or in the stop and go traffic. The refrigerant in it is in the right amount. What could cause this? Thanks.

The A/C system pressures would need to be checked to see if it is low on refrigerant. A low system will not cool as good at idle as it would on the highway. The fans need to be working correctly. If the A/C starts working when you are going fast, then the fans are not needed as much and the A/C might seem to work okay. I recommend having a mechanic check the A/C operation and the cooling system fans to make sure they work. This should address the lack of A/C cooling once fixed.

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: Vent system malfunction

It is highly unlikely that these two issues are related. The issue you are likely having is that the mode door actuator has failed. The mode door actuator controls the mode door which will move in different directions to block...

Q: My car will turn on and idle for maybe 2 minutes if I'm lucky and then shut back off

Hello. There are a lot of things that can cause this on your vehicle. If it will run for a few minutes or so, then that usually means that something is shutting down such as the ignition module or the...

Q: Car fans stopped working

The brake pads on most vehicles are metallic type brake pads and may exhibit a metal grinding sound that may be normal or the brake pad being worn can make the same sound. The best recommendation is to have your...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
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...