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air conditioner - compressor or clutch?

I do not know how to tell if the symptoms I am having are the clutch has failed or the AC compressor has failed or is about to. This started a while back when the compressor would turn on and sometimes I would hear a screeching sound that was brief at this point I was seeing a 35 to 40 degree difference between outside air and the vent temp on recirculate on fan speed 2.

One day the screeching rapidly became more consistant, every time the compressor turned on it would make this sound. I turned the ac off for 30 minutes and when I tried it again the screeching sound was longer and very consistant every time the compressor turned on. The ac was still cooling but I would estimate only a 20 degree difference.

I am thinking that the clutch is at the point where it is not able to engage properly and is slipping. But never having had a compressor or a clutch fail before I don't know the symptoms of how either of these fail.

I would appreciate any help in how to distinguish. I have a shop lined up that will pull the r134a out of my system (had the conversion done a few years back at a volvo dealer). The car is a 1990 740 with the original compressor. I want to do the job properly and if the compressor is the problem I gather the system will need to be flushed. I have never flushed the system before and will have to find out what is involved to do this as well.

any help is welcomed thanks MR

Reply to
My_roller2000
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Checked the belt tension? A loose belt will slip and screech.

Gary

Reply to
Gary Heston

Gary, I should have mentioned the belt tension looks good. I watched the compressor kick in when all the noise happens and the belt does not appear to be the issue. Other thoughts welcome MR

Gary Hest> > >I do not know how to tell if the symptoms I am having are

Reply to
My_roller2000

Mike, I am leaning towards your suggestion of replacing the entire assembly of compressor and clutch. Long ago I suspected an extreemly sloooow leak in the front of the compressor. I assume a seal. Over the years there is an oily residue in the belly pan which has gathered dust and debris from driving. I will look for iron filings in the pan as you suggest.

How does one determine if the compressor is failing and dumping particles in the system?

Assuming it is the compressor, any advise on the best way to flush? Products to use? I gather the accumulator and the oriface tube must be replaced as these will collect particles, if there are any. I am new to these steps.

Guess I am hoping the I got wise to this early enough that I don't have a failed compressor and all the junk in the system.

Other thoughts welcome MR

Mike F wrote:

Reply to
My_roller2000

Many Volvos use a Compressor drive belt that is very heavily loaded. If you use a US spec. belt it will only work for a few weeks. The true metric belt has a different contact angle than the "equivelent" belt that you buy at your local auto parts store. This is one of the items I go to my dealer for. Of course you could just over-tighten it and were out the clutch bearing. Try belt dressing. If the squeel stops when you spray a little on the belt, the belt is bad. Belt dressing won't quiet a clutch.

Reply to
ALRHALL

A lot of the stuff will collect at the orifice tube, simply because it has a very fine screen to prevent the orifice itself from clogging. So just removal and inspection by someone familiar with the system will tell you if the amount of filings is normal or if the system needs to be flushed. There are flushing chemicals available just for this purpose. Keep in mind the more you dismantle the system the better the flushing job will be, but the more likely you are to break some of your 13 year old parts.

Reply to
Mike F

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