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Old 06-13-2012, 08:18 PM
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Compressor Question

I know this is not for a diesel but it is a Mercedes and I figured I would get the best answers here.

This is on my 98 E430.

I had a leak in the AC. If I added refrigerant the AC would work great for about a day then nothing. I found the leak in the condenser so I replaced it along with a new dryer. I took everything apart and flushed the evap and hoses and dried them out. I flushed the compressor on the bench with the new ester oil. As I was putting everything back together I added about 5 ozs of oil to the compressor suction port and about 5mL each to the dryer suction and condenser suction. Then I spun the compressor about 10 times. I pulled vac for at least an hour maybe 2. Then I set my charging machine to 2lbs 3ozs and started to charge.

The compressor started spinning and cool air was coming out of the vents. About 1/3 of the way through the charge some refrigerant blew out from somewhere around the compressor. Then I noticed the compressor stopped spinning. I assumed it was due to refrigerant leaking out. But after I turn off the car the compressor was too tight to spin. So I called it a day.

Next day I come back out and the compressor spins freely. So I try again and the same thing happens. It appears like the compressor is trying to spin but it gets too "tight". It will return to normal spinning after letting it sit.

I assume the refrigerant blowing off is a loose connection on the discharge of the compressor. But what is going on with the compressor getting tight and then returning to normal as it sits? Is it some sort of liquid/vacuum lock thing?
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  #2  
Old 06-13-2012, 11:11 PM
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why are you using ester oil? I think it's mostly for R12 conversion cars...

check with the dealer or local parts counter for the correct oil your car is supposed to use.
likely pag 46 or so...

the compressor may have a pressure release port on it... some do. I am unfamiliar with your vehicle.
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  #3  
Old 06-14-2012, 08:32 AM
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Quote:
Originally Posted by vstech View Post
why are you using ester oil? I think it's mostly for R12 conversion cars...

check with the dealer or local parts counter for the correct oil your car is supposed to use.
likely pag 46 or so...

the compressor may have a pressure release port on it... some do. I am unfamiliar with your vehicle.
I'm using ester because that is what I have on hand from my other cars and it is compatible with r134.

Any idea what could cause a compressor to get "tight" and then loosen?
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2004 E320 Wagon

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

Last edited by Graplr; 06-14-2012 at 05:49 PM.
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  #4  
Old 06-14-2012, 01:19 PM
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Is it possible for the expansion valve to plug completely, causing the compressor and outlet side to hydrolock? Then the excess bleeds off over time, and lets you repeat?
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