A/C questions (one PW, one not)

[LKelly]

I've got a couple A/C questions, one on my PW and one on my 'other' vehicle...I decided that since one of them pertains to my PW, then maybe it could go in the Power Wagon section.

The air conditioning on my PW still works great, but in the last month or two I've been getting a really loud 'clunk' when I first engage it...which seems to be the clutch locking up on the compressor. Once it locks up the first time, it seems just fine - but that first time it sounds like someone took a sledgehammer and smacked it into the engine block (yes, it's that loud). My question is this: I'm guessing it's the compressor clutch assembly, though I really don't know for sure...and I'm not sure if there's any point in replacing it now, or if I should just wait until it dies altogether. I thought it might get better the more I used it, but it still makes the same noise every time the truck is parked for a day or two...and as far as I know, there really aren't any user-serviceable parts short of replacing the whole clutch assembly. Maybe I just need to turn the radio on really loud before I engage the A/C for the first time, so that I can't hear it.

The second question is more of a general A/C question, as I really don't know jack-squat about how the compressor assembly works. On my other vehicle, the bearings went out on the compressor - which I double-checked by taking off the belt and turning the pulley by hand. It made a loud grinding noise, and burnt pieces of something (clutch?) fell out the bottom when I rotated it...which wasn't a big surprise, because it sounds like a steam whistle when I start the engine (and it smells like it's about to burst into flames). Needless to say, I'm not driving that vehicle right now.

Anyway, for a variety of reasons I'm going to take that vehicle into a shop to have it fixed - but I'm not sure how the bearings work on an A/C compressor. Are they part of the clutch assembly, or will I have to have the entire compressor replaced? Like I said, I'm not planning to work on it myself...I just don't want to look like an idiot when I talk to the mechanic.

[06powerwagon06]

I had the same thing with my PW as you did. Loud clunk when the clutch engaged. I didn't wait for it to crap out though. I found an AC clutch on ebay for $75 shipped. Pretty easy to change if you are somewhat mechanically inclined. Works like a charm now!! Good luck It sounds like the other vehicle will be getting a new compressor soon.

[LKelly]

I had the same thing with my PW as you did. Loud clunk when the clutch engaged. I didn't wait for it to crap out though. I found an AC clutch on ebay for $75 shipped. Pretty easy to change if you are somewhat mechanically inclined.

Thanks for the response...and yeah, I should probably just replace the darn thing before it breaks. Normally I wouldn't worry too much about it because I have two vehicles and don't take the truck on long trips, but apparently they both decided to have problems at the same time.

At least I can get to the parts on the truck...on the car you have to come in from underneath, and I had a hard time even getting my hand in there far enough to touch the pulley. I miss the old days when there was so much room underneath the hood where you could climb right in there to work on stuff...and when we had V-belts, and I could just disconnect one accessory at a time.

[coder]

I had the same thing with my PW as you did. Loud clunk when the clutch engaged. I didn't wait for it to crap out though. I found an AC clutch on ebay for $75 shipped. Pretty easy to change if you are somewhat mechanically inclined. Works like a charm now!! Good luck It sounds like the other vehicle will be getting a new compressor soon.

What do you mean by "AC clutch"?

[LKelly]

What do you mean by "AC clutch"?

Assuming we're both talking about the same thing, I'm talking about the assembly on the front of the A/C compressor that determines whether or not the pulley is driving the compressor or just free-wheeling. When the A/C turns on, the clutch is supposed to lock up to drive the compressor - and that seems to be what's making the clunking noise. The cooling fan also starts up, but it's an electric fan and if it made a clunk that loud there'd probably be a major problem.

I've seen some posts which seem to indicate that the engine-driven fan is related to the air conditioner, but at least on my truck that isn't the case at all - that fan is for the engine only (and the tranny/power steering coolers), and the separate electric fan on the driver's side is for the A/C. However, mine's an '05...maybe they changed that in the later trucks. The whole two-fans thing is a bit odd...

[LKelly]

In my searches on the intertubes, I stumbled across this - which might help answer my question about my 'other' vehicle. From the heat (and the smell) I'd guess that my compressor got hot enough that it's permanently damaged. I also found a video of someone replacing the entire a/c compressor on my exact year and model vehicle, and I'm *definitely* not going to do that myself...it looks like I'd have to be double-jointed and have 38 fingers to do the job properly. And I was right, it all has to be done from underneath the vehicle.

----------------------------
Replacing the A/C Compressor Assembly vs Clutch Assembly

When diagnosing a failed A/C compressor/clutch assembly, keep in mind
that there are several possible causes for the failure, and that the least expensive
repair may not completely and permanently fix the A/C system.

An example of this is when an A/C clutch is replaced. What may appear
as a simple clutch failure is very often the result of other system problems, such
as oil starvation (due to loss of refrigerant or restricted flow), low voltage to the
clutch coil or extreme high pressure (due to clogged condenser, non-operating
condenser fan, improper refrigerant or overcharge). If high-side pressure climbs
to any excessive amount, the compressor will get extremely hot, and the grease
will melt out of the clutch bearing and cause rapid failure. These conditions will
damage internal compressor components, and just replacing the clutch assembly
will lead to another failure. The only way to properly repair this type of failure is
to diagnose the entire system, replace the compressor/clutch assembly, replace
related items (accumulator/filter drier, orifice tube/expansion valve etc.) and
thoroughly flush the system.

Also be aware that a clutch failure for any reason can damage the
compressor shaft seal, nose, and bearing, and this damage may not be
immediately visible. The heat generated by a clutch failure can distort the nose
on any aluminum compressor, which will cause the replacement clutch assembly
to fail. In these cases, the entire compressor/clutch assembly should be
replaced, along with complete system repair.
--------------------------

[06powerwagon06]

I had the same thing with my PW as you did. Loud clunk when the clutch engaged. I didn't wait for it to crap out though. I found an AC clutch on ebay for $75 shipped. Pretty easy to change if you are somewhat mechanically inclined. Works like a charm now!! Good luck It sounds like the other vehicle will be getting a new compressor soon.

What do you mean by "AC clutch"?

LKelly pretty much has it right. If you don't have the AC button on in the truck then the clutch isn't engaged and the compressor don't spin. When you press the AC button on then that sends a current (don't ask me what) to the clutch to engage it and spin the compressor.

[06powerwagon06]

It is true that there could be a lot more problems within the AC system then just the clutch. I guess I should have mentioned that I did a dye test on mine and after determining there wasn't a leak I made sure the correct pressure was in the system just as a precaution. Swapped out the clutch and its worked fine ever since. No more loud clunk when the clutch engages.

[bones]

Keep in mind most A/C cluthes also engage for defrost mode.

[LKelly]

Well, I finally got around to getting the car fixed - though I haven't fixed the PW yet. Apparently having an actual professional replace your A/C compressor (and all the associated parts with it) costs about $600. Ouch! But, now it blows 38 degree air - which is probably better than it worked when the car was new.

While I was at it, I checked the Power Wagon - and it appears to run between 44 and 45 degrees when recirculating, which isn't actually that bad. It would appear that all the various doors and flappers are still working properly at this point...at least for now.

I suppose the A/C in the PW could work a bit better, but that's one advantage of having a regular cab...less area to cool.

[MSparks909]

My A/C clutch is clunking as well Looks like it's back to CarQuest for a new A/C clutch! It honestly is never ending with these trucks...