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  #1  
Old 06-25-2004, 10:33 PM
lietuviai's Avatar
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A/C compressor going kaput?

My '85 300D's A/C compressor started making some intermittent loud low pitch squeaking noises the other day but they are only noticeable at idle and only when the clutch engages. It isn't a squealing noise a loose belt would make but more like a sound a bad bearing would make without the rough growling sounds. It goes away when the engine speed is increased. Otherwise the A/C still works fine. Is there a way to lube the bearings from the outside or should I start looking for a new compressor?

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84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012
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Old 06-25-2004, 10:55 PM
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Your ac system may be low on oil. Have you had any leaks in the system? Are there oily places at connections or on back or front of compressor. If so you need to add some oil ASAP. Do not run compressor until you have it checked out. Oil is a lot cheaper than an compressor and drier and flushing, freon etc.
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Old 06-25-2004, 11:20 PM
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As far as I know I haven't had any leaks, at least none that I have noticed. Is there a way to add oil to the system w/o evacuating and recharging it? My understanding of an A/C system is that it is all sealed and adding anything to it is nothing short of having to evac and recharge.
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Old 06-26-2004, 12:01 AM
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The clutch pulley bearing, when in early failure, can be quiet in "free spin", but noisy when comp. engages and puts it under load.

There are tools to add oil to the refrigerant w/o any loss of gas. Here's an example: http://jcsonlinetoolshed.com/product.php/1302/914//6cd02c948e14893d87335ea357c06cd9
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Old 06-26-2004, 12:01 AM
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There is an inexpensive tool to add oil to a charged system, it squeezes the oil into the service port. But, I don't know of a good way to check the oil in a charged system. Too much oil is not good and without checking the oil, you don't know if you need oil.
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Old 06-26-2004, 12:40 AM
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You sure its not the belt. My wifes AC belt was very very loose. Ironically lose enough that it didn't squeal but not so loose that the compressor didn't function. Sounded alot like a clutch problem when the compressor kicked on and got quieter as RPM's increased. Watching the belt you could see it jumping around as the compressor was spinning.
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Old 06-26-2004, 07:41 AM
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I have been having the same problem. My comp was making the same noises a year or two ago. I replaced the comp and the drier. Put it all back together, had it evacuated and recharged it. It still makes the same noise! When the ac is off the noise goes away. As soon as you hit the button the noise comes back at idle and goes away as speen increases. I was leaning toward another component in the front of the motor. Does the ac share a belt with anything?
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  #8  
Old 06-26-2004, 09:56 AM
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If you need to add oil, you can buy a product at Auto Zone, made by EF Products part #203. If they do not have it in stock the manager should order for you. Also you can buy oil charges that contain about 2 ozs of r12 off of ebay. Sell for about $11. for each can.
Would definitely check out the belt tension first. There are ways to check the oil quanity, if you have the right equipment.
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Old 06-26-2004, 04:17 PM
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Thanks for tips everyone. I'm going to pull it into the garage today and check it all out thoroughly.
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  #10  
Old 06-26-2004, 08:55 PM
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Well I am embarassed to admit it but all it was was a looose belt. The first thing I did, even thought the belt felt like it was tight enough, I tightened it some more and when I started the engine, turned on the A/C, the sound was gone. I then went ahead and tightened all the belts.
Stay tuned for a possible new thread, "Tightened the belts too tight, belts broke".
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Old 06-27-2004, 02:00 AM
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jba,

FYI the clutch bearing spins when the compressor's internals are not. The idea being that the pulley can rotate around the clutch with the engine running. Engage the clutch and the bearing is no longer "spinning."
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Old 06-27-2004, 02:19 AM
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Thanks for the heads up. The noise issue would, of course, be the opposite of what I said.
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Last edited by jbaj007; 06-27-2004 at 10:34 AM.
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  #13  
Old 06-27-2004, 04:07 PM
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Cool

Glad to hear you got it fixed. Sometimes the fix is very simple. Happened to me on a trans. , the vacuum line came undone, cost nothing to fix.


Give a man a fish, you feed him for a day, teach a man to fish and you feed him for a lifetime.
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  #14  
Old 06-27-2004, 04:52 PM
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Quote:
There are ways to check the oil quantity, if you have the right equipment.
If you see some information on this, I am interested. I am still learning about this stuff and I am not clear on this point.

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