Air Conditioning whine after turning off engine

Hello aztec626bf; I'm having trouble recieving your answer on this issue. It happens both ways, when the AC unit is on and also when I turn off the AC and then shut off the ingnition. thanks, russianfrog

Sorry, but going to have to ask a few more questions to narrow it down. 1. Is the noise more like a hiss or a whine? 2. Is it louder inside the car or outside? 3. Have you tried shutting the car off with the heater control in the off position? The ideas I am having are as follows; 1. The noise might be the vacuum escaping the vacuum system when the engine shuts down. 2. If you have the heater control on defrost the A/C pump is still on and the sound could be the refrigerant passing through the expansion valve. You can eliminate this by making sure the heater control is completely off when shutting down the car. Let me know on these items then we can go further.

Hello aztec626bf, The noise is definately a whine or moan. The noise is equally loud inside and outside of the car. People walking by, look at us as if it's going to blow up. The heater control is completely shut off and it still whines. thanks, russianfrog

Am I understanding this right that it only does it once you shut the car off? While the car is running there is no noise? This makes a difference so we can eliminate a belt squeal. From what you said in last post I don't think it is the two items I mentioned in my last post.

did you ever figure out what this was??? having same issue with our 06

Our 2004 Rendezvous has been doing this since we got it in 2004. Had it to the dealer several times and was told it was normal bleed down. Would really like to find out what is causing the noise. It's really embarrassing.

Really?? No one could find the answer for this? I have a 2004 rendezvous that is doing the same thing