I posted a while back on my 2002 Chevy Venture. We took it to the Chevy dealer as it was blowing out warm air. After a lot of component changing ( do to misdiagnosing) they finally got it right and it has been working fine now for about 3 weeks. They changed the condensor, most of the lines and the rear evaporator coil. Now another problem has seemed to come up although the A/c is working fine. It seems when the vehicle has sat for 2-3 days and hasn't been used, when you start the van up it runs fine however, as soon as you hit the A/C buton on, there is a loud vibrating/buzzing noise that lasts for about 2 seconds then goes away. You can feel the vibration on the floor board with your feet. You can then turn the a/c on and off all day and the next and you won't hear or feel it at all anymore. Only when it sits for a few days again it happens. The A/c is working great other than that. Almost seems like the A/C clutch, but not sure why it would do that. Any thoughts, could they have caused this with all there work they did on it. They were supposed to have checked this whole system out very thouroughly. Thanks

 

It sounds like there may be a line that is too close to the floor of the vehicle and after the freon equalizes the vibration is caused by initial circulation. I would try to verify this if possible. But I would definately consider taking it back to the dealer to get them to correct this.
Hope this helps ya,
Billy

 

I can take it back to them to look at however, it's like you only have one shot to hear this and then you have to let the ac sit dormant for a few days so this may be difficult to pinpoint. My concern right now is with the compressor and that something hopefully has not gone wrong with this. Im not sure exactly how they work but being there is a clutch on there, is it a possibility that if the compressor sits idle for a few days something seizes in there slightly and when you go to engage the compressor you get this noise in the compressor or clutch until it breaks free. I could be off base there, but please advise what the symptoms are of a compressor that is failing. In the meantime, I'll call the dealer back and have them look at. Thanks

 

1. clutch comes on and off continuosly, as a/c system recirculates freon. you should feel nothing/slight click/maybe slight loss in performance, as it takes some power away from the engine to run compressor. if you have engine powerful enough, should be unnoticeable.
2. why do i have that feeling that you have either air, or moisture left in the system and it simply "bubbles" in the lines when it starts working, or it entered the system after repairs and is causing resonance?