Clunk when starting a/c

[pwknapp]

Yep. Start the new '07 Mega, turn on the a/c within a couple of minutes, and get a serious "clunk" sound. Anyone else experience this?

 

[roperteacher]

There have been quite a few reports on this. It seems to be very normal for these trucks. As I understand it it's the compressor kicking in. I noticed on my 06 that if I let the engine run a minute before turning on AC it wasn't as bad. I just bought an 07 today and it sure didn't clunk as of yet...

 

[DPKetchum]

Been clunking since 03.

 

[PRattenbury]

Mine clunks, but not every time.

 

[69RoadRunner]

Mine clunks, but not every time.

Ditto on my 06 Mega.

 

[JNeeley]

Twice when I've started my 07 just sitting in truck for a second and I noticed what ya'll describe as a clunk. The first time it did it, it felt almost like someone was walking by in my company parking lot and bumped the truck just messing with me, I mean I could really feel it but there was no one around. It did it again a few days later. I'll pay more attention to see if its when AC kicks on but its so random I don't know its happening.

 

[ModifiedDiesel]

The 6. 7L still has the clunk also.

 

[Jeepr]

Yup, it's a standard "feature". Kind of like the belt chirp when you turn it off. It's these quirks that make us love our trucks! (no, really, we do love them, right??)

 

[LesStallings]

If the clunk if from the engine compartment, I would not worry. If the clunk is more of a fairly loud "thunk" from under the dash, be worried about eventual failure of the AC blend door and/or recirc door. Both are common failures on 3Gs.

 

[TRLRTRSH]

Yep my "03" clunks everynow and then.

 

[SuperSteeler]

Same for my 04. 5.

 

[MStrain]

Mine clunks half the time when I kick on the AC, so does my brothers 06, must be standard, it does sound like something is breaking or broken though.

 

[TKeeler]

I heard this noise just the other day as we are now needing AC and I associated it with the 'recirculate' switch and it being a damper closing off fresh air from outside. I will pay closer attention here the next few days as we hit over 100 degrees yesterday which is rare for here.

 

[Ross]

Mine clunks, since new. I wonder if DC charges extra for this feature?

 

[Spooled-up]

My '07 5. 9 clunks too. I can actually feel an rpm drop when it does it and it shakes the whole truck. I remember reading recently where a guy took it to the dealer for this and they actually changed something out to help it. I think it was in the Weak A/C thread.

 

[timroberts]

04. 5 clunk when new now have 75,000 miles. But not every time A/C turned on just first time after sitting all night.

 

[CStockton]

Mine clunks... it's one of the hvac doors.

When it stopped clunking is when the ac didn't work as well. The dealer replaced the complete hvac housing and ac works better than new but it still clunks.

I like the clunk.

 

[DPKetchum]

You might have had a hvac door in the dash clunking but I think the clunk being addressed is the CLUNK when ac compresser engauges from under the hood.

 

[AKaiser]

Don't have a "clunk" from the compressor. Mine is definitely a door closing.

 

[SHobbs]

Clunker here as well, not every time and really have not heard it in a while. Kinda scary the first time you hear it.