A "clunk" when turning on AC

[bkmelton]

My wife claims (and why would I doubt her fellas) that when she turns on the AC (truck has to be stone cold) there is a "clunk" she can hear and feel (through the floorboard/pedals). She says it is more of a "kalunk". I don't use this truck (06 2500) and never use the AC (we live on the CA. North Coast). The AC works fine but none of our previous Rams (gassers) have made any racket upon initiating the AC button. I need to resolve another problem at a dealership tomorrow. What could this sound/event signify and would it best be brought up unrelated to my oil leak problem (AC specialist vs mechanic)? bkmelton





06 2500 Megacab no mods

 

[BimmerAgent]

Mine's done that since new, and I've not had any problems with it. It is kinda noticeable when the compressor first kicks in, buy after that, I don't hear any more "klunks". Bruce

 

[SDunkle600]

bkmelton,



Welcome to TDR. I have done a lot of research on the internet and on this forum on this and it seems to be a normal occurance on the third gen trucks. I have a 2004. 5 and it has done it since it was new. It is the worst when I start the truck after it has sat overnight. After looking into it and seeing others with the same problem, I don't worry about it anymore. I haven't had any problems relating to it either.

 

[lethal injection]

Mine also does that

 

[tdinut]

me too

Hi,



My '06 3500 qc sb auto just started doing that :{ . I've had it five months. I had to let it sit unused for almost 2 weeks and the first time I started it with no accessories on, I heard and felt the kalunk/groan. Now it does it almost every start-up, more often when sitting overnight. I can't decide if it is ac related or not. It has been perfect in every other way. Not sure what to do yet. I just wish I had more faith in my local dealers (Long Island). I will keep an ear on it. I LOVE MY TRUCK ...



Joe

 

[Prairie Dog]

This has been discussed many times in the last few years. It's normal.



Scotty

 

[LesStallings]

It may be normal, but my clunk just got louder right before the failure to cool the passenger's side. I can't help but think it is related. I believe I read that it is one of the ventilation doors that fail. Sticking with a sudden release may be causing the clunk, followed by eventual failure... no passenger cooling...

 

[TowPro]

As loud as it is, just think of the stress its putting on the drive belt when the compressor goes "clunk". I can even see the jolt in the tach as the motor drops rpm then recovers.

 

[Heavyweight]

CLUNK,,,,clack clack,,,, get used to it. If they sit for a few days, and you start the AC,,,,, Clunk, clack clack... . My 2005 has done it 10 times.

 

[MChildress]

My AC compressor does it too. Seems more pronounced after sitting for a couple days.

 

[rbattelle]

This has been discussed many times in the last few years. It's normal.



Scotty

Check out post #6.



Ryan

 

[mattk50]

mine does this as well. has since new. its normal.

 

[SteveMiller]

I'll just say that I know this doesn't make sense and it doesn't seem like it can be related but here's what happened to me. The clunk happened a few times and I even complained but nothing happend. Once or twice it really drug down the RPMs and I'm pretty sure it was just the A/C clutch kicking on. And as long as its working I agree the clunk isn't much to worry about... until the clutch gives out from being banged on. Anyway, I then got the vent door failure (on a 105 degree day) and took it in as soon as i could. They fixed the door and I haven't noticed the clunk since. I continue to listen for it and it hasn't happened. I can't imagine they are related, unless the clunk wasn't what I thought. Maybe its just coincidence.



2006 qc 4x4 sb

 

[bkmelton]

OK, so... . we have a majority agreeing that it's normal. I'm going to keep my ears open (as I've explained, only my wife has experienced the noise) and I'm going to go over my warrantee again. Thanks alot for all the feed-back! I do feel a little better. BOB

 

[Sulls]

Mine just started clunking this last weekend. 2 yrs & 22,000 miles.



4. 5 QC 2x4 short

 

[MMeier]

FWIW, I haven't noticed mine go "clunck" or what ever you want to call it since I added a can of R134 to the system. Makes me wonder if that is not another penny pinching operation by DC. You know, no underhood light, sound pad, low lube levels in various drivetrain parts when new, etc.

 

[mwilson]

Talked to my dealer Saturday about loud clunk / harsh engaging of A/C clutch and tech told me of a flash to make BCM apply voltage in steps rather than all at once. Has flashed one already and says you can hear the difference upon engagement. He says D. C is worried about compressor shaft shearing due to shock load. Mine really bangs when it has a fit. He claims that high side pressure is still up and no or very little low side pressure makes the clutch engage so violently. It makes sense to me as I think about it because every time it has done this it has been the initial start up the next morning after an afternoon of running with A/C on. Maybe this is the fix. I have an appointment on the 26th to get the flash. I will post results.