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  #1  
Old 08-03-2007, 09:47 AM
Gene
 
Join Date: Mar 2007
Location: Buffalo NY
Posts: 1,102
About 1/2 hr worth of AC in a W124 ???

Folks, I ran searches last night, adn some this am, guess I need to learn to use the Google search on this domain... since i'm
sure the answer is here somewhere...


What would cuase the symptom of the AC gradually getting warm after maybe 1/2 of run time. Starts off very cold. Then becomes warm over a 25-35 minute period. Steady 2700-ish rpm on the highway. Did it yesterday at 93 ambient, and this am at 76 ambient.

Only time I've had it checked was after a higher rpm romp, the system shut off, and the radiator/AC shop checked it and found too much pressure in the system.

The AC does effect milage and 0-60 times, a decided load on the engine.

Supplemental electric fans do come on low when the system ( or engne) build temp. WOuldnt mind having an in-cabin switch to put those puppies on high when its cooling.

Thing is, since the system works somewhat, I am tempted to leave sleeping dogs lie. Would sure hate to fix it , only to have the famous and well hidden evaporator go. But if its no more than replacing a loose compressor, its not a bad use of $$$.

Dont have a good indy ID' d yet, but wont do this in my garage, dealing with coolants and all.

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Old 08-03-2007, 10:25 AM
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Join Date: Feb 2002
Location: Virginia
Posts: 550
Well, the two things that jump out to me are monovalve issues - which I believe to be considerably less problematic on the 124 than the 123/126 - or that something electrical is causing your compressor to drop off line. What refrigerant are you running? R134a?
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  #3  
Old 08-03-2007, 10:53 AM
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Join Date: Jan 2006
Location: my own little world
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had similiar problem in a jag once. Condensate drain was bloked. ac would work until the evap started to fill with water , ac got warm and wet. after car sat a while water would slowly drain. ended up blowing out lines and all was ok for a while, until car was sold.
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  #4  
Old 08-03-2007, 11:34 AM
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Quote:
Originally Posted by WINGAS View Post
What would cuase the symptom of the AC gradually getting warm after maybe 1/2 of run time. Starts off very cold. Then becomes warm over a 25-35 minute period.
If your compressor is desengaging and causing the "warm air" condition, I would suspect the evaporator temp regulator. It's function is to prevent the evaporator from freezing, but sometimes they fail and "trip" at a higher temp than specified.
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  #5  
Old 08-03-2007, 11:47 AM
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Join Date: May 2002
Location: Blue Point, NY
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Quote:
Originally Posted by tangofox007 View Post
If your compressor is desengaging and causing the "warm air" condition, I would suspect the evaporator temp regulator. It's function is to prevent the evaporator from freezing, but sometimes they fail and "trip" at a higher temp than specified.
And, if the compressor remains running during this period, I'd be almost certain that the expansion valve opens to a larger degree than desired and fails to give the required pressure drop.

A set of gauges on the system should confirm this.
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  #6  
Old 08-03-2007, 02:10 PM
Gene
 
Join Date: Mar 2007
Location: Buffalo NY
Posts: 1,102
Its R134a btw. I dont see a huge puddle of h20 under the beast as I should. I'll check the drain, if that's not it, off to the radiator/ac shop it is. Plus, dont want evap to oxidize up, hear its a real job in the 95. Hopefully a line cleaning is all it needs.

I dont want to learn about the "monovalve" just yet!

Thank you all.

Gotta find that drain. First look and I cant see anything.. yet..

Last edited by WINGAS; 08-03-2007 at 05:55 PM.
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  #7  
Old 08-08-2007, 09:39 PM
Gene
 
Join Date: Mar 2007
Location: Buffalo NY
Posts: 1,102
System checked out OK, drains are now clear. Seems like the compressor doesnt cycle much after the first 1/2 of run time is all.

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