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

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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.

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