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AC Clutch Bearings Making Noise

GlennJD on Tue November 06, 2007 2:22 PM User is offline

Year: 1995
Make: Dodge
Model: Grand Caravan
Engine Size: 3.3 V6
Refrigerant Type: 134a
Ambient Temp: 50F
Country of Origin: United States

I've been chasing down a squeak in my engine serpentine drive belt, following putting a new engine in my van. I have a new alternator, new water pump, new idler pulley, new belt tensioner, and a new drive belt. I have cleaned all the pulleys (everything is spotless). I have this squeak that starts as soon as I increase past idle. I've pulled out my stethoscope and isolated the sound at the AC Compressor. It gets louder as the engine RPM's increase. It diminishes a bit when the AC Compressor engages but it is definitely still there. My question is, did I do something during the engine replacement that damaged the compressor. I folded back the compressor and hoses while I did the engine to keep from having to open up the system. There was no noise from the compressor prior to the engine replacement. It is short cycling now and I haven't yet had time to put the gauges on it (I also have to borrow a my buddy's shop so I can get 80F ambient to take the readings).

Is this something that can be taken care of by replacing the AC clutch? If so, what's the procedure on this van for doing a clutch replacement? Any advice will be gratefully accepted and applied!


James Glenn
Pleasant Grove, UT

bohica2xo on Tue November 06, 2007 5:28 PM User is offline

You have a couple of problems here.

1) A failing clutch pulley bearing. Remove the belt, and turn the pulley by hand - is it smooth, or can you feel the balls in the bearing?

2) Low refrigerant charge. The added strain of re-locating the compressor may have caused a leak.

The simple (and expensive) answer would be a new compressor. If you want to fix what you have, look at the bearing first. If the bearing has spun on the compressor snout, you are done. If the bearing has not gone that far, check the shaft seal next. Once you have fixed everything behind the clutch, adjust the shims for proper clutch gap & put it back together.

Finding the leak is next. It may have been the added strain on the fitting at the compressor caused a leak. Or flexing the hoses that far was too much for them. Perhaps the transmitted force caused the other end of the hoses to leak... If you do not have a good sniffer, I would add some dye to the system and charge it up. Run it daily for a few days & have a look.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

GM Tech on Wed November 07, 2007 8:23 AM User is offline

I've seen 2 or 3 Caravans have belt squeaks that you can't get rid of-- new belts no help-- I test by using a small stream of water on belt- noise goes away- then comes back in about 10 seconds- this way I know it is not a bearing- only the belt to pulley interaction- I have seen TSBs on Caravans- I have a buddy been fighting his for over 2 yrs- has had new tensioners, new belts- still no help- yet it is not a bearing- since every time he wets the belt- the noise subsides- I would test with water before I replace components if I were you- just to be sure-- I'm inclined to say the belt noise is a "Chrysler thing" ,...................

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

ice-n-tropics on Wed November 07, 2007 10:12 AM User is offline

Ditto to all GM Tech's comments. If any front engine drive accessory is the slightest bit out of line (1/64") or the vee groove machining on any pulley is a few thousands off, the noise increases. Belt dressing just gums up the grooves and the noise returns. Also, I think this vehicle has a too small diameter alternator pulley, which increases the slip % when the electrical load is high and the belt glazes over easily.
I've observed that Caravan routes the sweating suction hose directly above the serpentine belt. On high R.H. days the dripping condensate on the belt can cause an increase in the squeal, therefore I insulate the suction hose with high quality black sponge foam rubber. If you splash through high road water the belt screams, so park the van on rainy days -Hah, Hah. Also, the glaze on the grooved side of the belt can be buffed off with a wire brush while the engine is running for short term noise abatement if you are real careful (not for amateurs).
The best belt for noise is one which has diagonal grooves every 1/2".
Chrysler came out with a field fix for compressor pumping noise. It was a 2 pound weight attached to the suction hose about 10" from the compressor. They used the same fix on a car platform.
Hope this helps,
Old IV guy

Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy. How To Air Condition Your Hot Rod

Edited: Wed November 07, 2007 at 10:13 AM by ice-n-tropics

GlennJD on Wed November 07, 2007 10:45 AM User is offline

Thanks all. I had two problems. First, when I put the mounting bracket back on I didn't notice that there was about 1/16" of play in the mounting bolts to the block. So, I made sure that everything was dead center and torqued to spec. Next, I took ether and carefully cleaned every pulley with a clean cloth (especially down into the grooves). I also took 600 grit sandpaper and lightly buffed the guide pulley and the water pump pulley--the tensioner is new so I didn't do anything to it. Finally, I pulled off the AC Clutch and found.......a bad clutch bearing. I replaced it and it is blissfully quiet. Also, I use a NAPA brand drive belt. I gave up on the junk at Checker and Autozone a long time ago.

Now, on to the short cycling. I'll try the dye and see what happens. Is it possible to spot a slow leak with soapy water? I won't have time tonight, but I'll probably throw the gauges on Saturday and see what the numbers are.

Thanks for all the advice.

James Glenn
Pleasant Grove, UT

bohica2xo on Thu November 08, 2007 10:49 AM User is offline

Just add some dye, and bring it up to full charge. I would recommend an ounce of oil with the dye as well.

It is hard to say on a 10+ year old vehicle where the leak is. It may be that you were very close to the critical charge, and the leak existed before the engine replacement. It might be related to the movement of the compressor, or not.

Soap or BigBlu can be useless when the leak is small, or not in the line of sight. The automakers all add dye at the factory now, to reduce diagnostic time at the dealer level.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

NickD on Thu November 08, 2007 6:52 PM User is offline

What about something like this?


? 0.4 oz./yr. sensitivity to CFCs,
HCFCs, and HFCs
? Automatically compensates for
changing background
? Variable intensity audible signal
and single flashing LED help
locate leaks fast

For a couple of hundred bucks, would pay for itself in a hurry if you are paying some shop using a high school kid guessing at 80 bucks an hour, then you will always have the tool. And you can have very strong faith that you will have another leak again.

Gas can escape without leaving a trace of oil or dye.

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