A/C Compressor Clunk on 2007 GMC Sierra

[snfexpress]

Whenever my A/C compressor kicks on at low idle, it creates a clunk and noise - the clunk can be felt through the brake pedal. The local dealer is telling me that this is "normal".

Anybody else?

[SlickWillie]

Never notice the compressor kicking in and out on the 04 GMC. You might want to get on DP site and see if there are any bulletins on this sort of issue. I know some of the 04's had some issues (IIRC they were cooling issues). Ours had the same compressor that had the service bulletin, but we've never had any problem with the AC. (knock on wood)

[Ozz]

When it comes on, a magnetic clutch engages,then the compressor engages, it requires a degree of horsepower. On low idle, this would be a significant event. These A/C units are quite powerful, and do require the engine to labor at low idle.
I don't know if this is normal for your unit or not, but it is possible the compressor is 'tight' causing abnormal conditions. You will not notice the difference in cooling, if bad, it will get worse.
Good luck Michael.

[skypilot]

Have the same issue with my Dodge - it 'clunks' very loudly the first time it engages after sitting overnight or longer. Dealer said it is 'normal' (or at least not replaceable under warranty as yet) and to keep using it. They did make it a matter of record on my file though so that, if it should fail, the condition is documented for possible future warranty issue.

[Leaseit]

Michael, 2007 New Body Style Chev Duramax here. I can't even tell when the compressor engages. No Clunk, No Sound No anything. Sorry, but nothing when the electical-Magnetic clutch engages. Maybe mine isn't normal.
Hummm thinking, Maybe its not engaging and i don't know it, but it blows cold air. Just kidding, A/C license here so i think i'd know..
Randy

[snfexpress]

Thanks, everyone - and you too, Jim. I will "engage" my local dealer.

[Ozz]

You bet. My money is on the tight compressor. I run into these on the job all the time, I usually install a heavy duty start capacitor, as the tight compressors won't start with original small, or no, start capacitor.
The unit still functions, it just needs an extra 'hit' to get it going. My neighbor has one across the street from my stick house. This last Summer, it even blew a heavy duty start capacitor I installed 3 years ago. I put a new one in, and it's working fine.
I would doubt they do anything about it until it quits. I know you can tell stories about truck dealer follow through.........

[sreigle]

My 2003 Ford, my 2005 Ford, and my 2007 Dodge all have that same clunk but only after the truck has set overnight or longer. But all of mine have done the same thing.