Car air conditioner


#1

I have a 03 Pontiac Grand Am. When my car is idling, the air is ice cold, but when I take off, it changes to just cool and humid, and thats when i have it on MAX setting. Any Ideas what could cause that?


#2

Does your A/C return to normal cooling when you reach cruising speed?


#3

I’ve attached a link to a plethora of diagrams of how automotive AC systems are put together. And I could speculate on a specific cause. But since diagnosing and repairing AC systems requires epecial equipment and training, I truely believe the only advice I can offer is to bring the car to a shop that does AC work (often radiator shops also do this) and let them diagnose and repair it. Sorry.

http://www.bing.com/images/search?q=automotive+air+conditioning+system+diagram&id=0C027A404E5AE523EF6A14B0BEEA8940A71F0E1E&FORM=IGRE3


#4

I think the vacuum that controls the blend doors is leaking out on acceleration, most likely from a bad check valve. If the vacuum in the system drops, the blend doors open and allow hot humid air from outside into the air stream blowing into the cabin. A replacement check valve is cheap, and a competent A/C shop should be able to locate and fix this problem quickly.


#5

Some cars have a switch that turns off the AC compressor if you floor it, to eliminate the power drag of the AC when you’re trying to hustle. Are you flooring it when you take off?


#6

It could also be low on charge. When you accelerate and the compressor spins faster, there may not be enough refrigerant to maintain normal pressures–when the pressure falls below what the pressure sensor is calibrated to, the system cycles off.


#7

I would go for the vacuum issue. mentioned above.


#8

There’s also a remote possibility there is a loose electrical connection on the compressor, and the change in momentum makes the A/C stop working momentarily. If that’s the case, you’ll need a new compressor.