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  #16  
Old 06-04-2006, 05:50 PM
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Hi guys!!

Update: I suspect that my high-side pressure is getting too high! Why, because my auxillary fan stays on even after the AC has been cut off for over 2 hours!! I don't have gauges here with me at home. To be safe, I unplugged the compressor for now....I do not want to damage a brand new compressor if I have some type of blockage in the system......For whatever the reason, my gut is telling me that the expansion valve is blocked!......

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1999 E300 Turbo Diesl
2002 ML500
1995 E320 Station Wagon


MBs I've owned
1997 E320 Assassinated by Pine Tree
1987 300E Wife Killed Engine
1981 300D Stretch Limo Total Loss
1970 250 Coupe 212,000 mi.
1974 450sel 184,000 mi.
1974 240D 377,000 mi.
1977 300D 204, 000 mi.
1979 280se God Only Knows!
1983 240D 130,000 mi.
1972 220D 280,000 mi.
1983 300SD 244,000 mi.
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  #17  
Old 06-05-2006, 08:55 AM
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The aux fan is engaged via the temperature switch on the R/D. When it sees a higher temp on the R/D (52C is spec) the switch makes and engages the fan.

A longshot possibility here.....some aftermarket R/D's have only 9.5mm pressurized ports (like the one I bought). The original temp switch (with M6 thread) won't screw directly into it. They want you to buy a temp switch with a 9.5mm thread to mate to it. If the temp switch is in fact NOT a temp switch but a pressure switch, the aux fan would run and run.

I never noticed this difference on switch threads until I changed my R/D a few weeks ago. Not having another temp switch and not wanting it screwed into system pressure, I drilled and tapped a blind M6 hole into one of the 9.5mm port plugs and installed my original switch. Works fine.
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  #18  
Old 06-05-2006, 09:24 AM
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Quote:
Originally Posted by Pete Burton

.....some aftermarket R/D's have only 9.5mm pressurized ports (like the one I bought). The original temp switch (with M6 thread) won't screw directly into it. They want you to buy a temp switch with a 9.5mm thread to mate to it.
Just curious about the brand of R/D that you purchased. I have one on order (Behr) and I sure hope it's not like yours.
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  #19  
Old 06-05-2006, 09:47 AM
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I do believe that it is a Behr that I got. Aftermarket parts have to be designed to fit multiple applications to stay competitive. This one worked out for me as there were 2 spots available near the sight glass to mount the temp switch, and I was able to move mine away from being jammed up too close to the headlight housing knob like it was before. Either buy a new temp switch or D&T one of those plugs with a M6 - you have an extra anyway and if you don't care if the temp switch is isolated from system pressure, just drill right through the plug. Obviously, you want to remove the plug from the R/D before you drill it.
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  #20  
Old 06-05-2006, 10:09 AM
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Thanks, Pete. All I need is another complication. UPS should deliver this afternoon; I'll find out then. I just had to order a new vacuum pump, since the one that I borrowed will only pull 25 in/Hg. Then found an a/c hose with a blister, so had to order another hose. Maybe I'll get the a/c working before summer is over!!
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  #21  
Old 06-05-2006, 10:45 AM
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likely culprit....

Quote:
Originally Posted by Bigdaddybenz
Hi guys!!

Update: I suspect that my high-side pressure is getting too high! Why, because my auxillary fan stays on even after the AC has been cut off for over 2 hours!! I don't have gauges here with me at home. To be safe, I unplugged the compressor for now....I do not want to damage a brand new compressor if I have some type of blockage in the system......For whatever the reason, my gut is telling me that the expansion valve is blocked!......
If you checked the monovalve and it is OK then I would say your expansion valve is blocked, which is not too uncommon after a system overhaul and flush. The flush loosens alot of crud and not all of it comes out. Consequently when filling the system the new refrigerant and oil can circulate some of this remaining crud and it blocks the small orafice of the expansion valve line.

Try replacing the expansion valve, not too expensive, and when you evacuate the system again draw it down slowly to 29in. and let is sit for a while before recharging.

Hope it works out for you
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  #22  
Old 06-05-2006, 12:45 PM
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Quote:
Originally Posted by 87tdwagen
when you evacuate the system again draw it down slowly to 29in.
Why slowly? How slowly?
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  #23  
Old 06-05-2006, 01:00 PM
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a couple of reasons:

Quote:
Originally Posted by tangofox007
Why slowly? How slowly?
The slower the better, a couple of inches per hour would be the best to control and prevent rapidly boiling the fluids and gasses in there, doing so will ensure removal of most liquid vapor and physical contaminants in the system, which ironically will be harder to completely remove in a gaseous state..

Secondly is for the benefit of the seals, you are dealing with an old system, probably has original O-rings, hoses etc. These are designed to seal against pressure from within, drawing down a system too quickly will apply alot of negative pressure on these seals and introduce the possibility of creating a leak that didn't exist before.

One other note is you hoses. If you are switching to 134 you should replace your hoses to the new barrier type, 134 for all intense and purposes is thinner than R-12 and will eventually weep/leak thru your original hoses. Newer hoses will not leak in the same way.
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Last edited by 87tdwagen; 06-05-2006 at 02:16 PM.
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  #24  
Old 06-05-2006, 01:11 PM
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Quote:
Originally Posted by 87tdwagen
The slower the better, a couple of inches per hour would be the best to control and prevent boiling the fluids and gasses in there, doing so will ensure removal of most liquid and physical contaminants in the system, which ironically will be harder to completely remove in a gaseous state..
I thought that the whole point of applying the vacuum was to convert liquids to a gas.
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  #25  
Old 06-05-2006, 01:50 PM
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OK to some degree you are correct...

Quote:
Originally Posted by tangofox007
I thought that the whole point of applying the vacuum was to convert liquids to a gas.
When you draw vacuum you will convert liquid to gas, but if you draw too quickly the water vapor will actually condense to the point where it freezes, once you have ice in the system, that's it, nothing's coming out.

When you change the pressure of air positive or negatively very quickly you increase the chances of freezing the liquid vapor. Take a can of compressed air or your air compressor and quickly release the air, then feel the outlet port and you will notice it is cold to very cold Similar when drawing vacuum.

So you should draw you vacuum as slowly as possible even down to one inch per hour until you get past 10 inches, by that point most if not all of your vapor is out already and you can draw quicker from then on.

You should also apply some heat, a blow dryer works good to the condensor and especialy the dryer filter as you draw vacuum, this will allow the liquid to turn to gas and be drawn out of the system. Or you can just draw super slow until 29 inches are achieved, in this way you do not run the risk of forming ice or compromising the seals.

I hope that explains it a bit better.
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Last edited by 87tdwagen; 06-05-2006 at 02:12 PM.
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  #26  
Old 06-17-2006, 09:26 AM
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Update; Removed The Newly Installed Expansion Valve And It Was Clogged With Residuals From The Old Compressor's Meltdown....i Cleaned It And Reinstalled It, Flushed The System Again, And Now I've Got Ice Cold Ac!!!!

Thanks A Lot Guys, You Called It!!!!

Whod'a Ever Thunk It??????????

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Currently Driving
2006 E320 CDI
1999 E300 Turbo Diesl
2002 ML500
1995 E320 Station Wagon


MBs I've owned
1997 E320 Assassinated by Pine Tree
1987 300E Wife Killed Engine
1981 300D Stretch Limo Total Loss
1970 250 Coupe 212,000 mi.
1974 450sel 184,000 mi.
1974 240D 377,000 mi.
1977 300D 204, 000 mi.
1979 280se God Only Knows!
1983 240D 130,000 mi.
1972 220D 280,000 mi.
1983 300SD 244,000 mi.
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