If working on cars drove you crazy I'd been there a long time ago!! I purchased this car knowing the air and radio did not work. The compressor clutch was locked up. I have replaced the following in the a/c system. New dryer, txv, and reman compressor. Flushed the system. Charged the system today. I am using R134. Static pressure 100 lbs. Low pressure at idle 45 lbs. High pressure at idle 250 lbs. Air temp from center vents 78 degrees. I have heard that these a/c systems arn't great but I was hoping for a temp of 60 or below. Low pressure at 2000 rpm's 20 to 25 lbs. High pressure at 2000 rpm's 225 to 250 lbs. I know there is no water going through the heater core because I cut the rubber hose and plugged both ends. Is there an air flap that would cause the air to bypass the a/c core? I have had this car a year and would soon like to start driving it. Any help would be appreciated.

I was getting the same temperature out of my 420 SEL till I found the evaporator to be clogged full of pollen and Lord knows what other crap. This highly reduced the air flow. Now I get a temperature of 42 F out of the center vents and my son telling me he's to cold and to turn it off!

Hope This Helps!

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William
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1987 420 SEL - Like a fine wine only better with age

Thanks William,
How did you clean it? Do you have to remove it from the car? If so I see a major dash removal!!

I fitted a new one with an already connected expansion valve. This is a dash out operation and requires some time and patients. To clean it you would have to blow it out with air in the opposite direction. But for a hundred and forty bucks off of e-Bay for a brand new one. Well... you can see which is the logical direction. Unfortunately these vehicle came before the pollen filter and definitely show the reason why the filter is needed.

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William
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1987 420 SEL - Like a fine wine only better with age

On a car that was originally R12 - shall we assume the car has been converted?

The car was R12 but had no freon when I purchased it. I decided to use R134a because all of my other cars have been changed over. I flushed the system and put in the correct amount of PAG oil. I changed all of my other cars when they leaked out with no problems.

What is the temp of the suction line (low pressure) where the service valve is ? Does it feel cold ? I am not sure that there should be such a large variation in suction pressure when you go from idle to 2000 rpm. 78 deg means the cooling is very weak. Is the belt nice and tight ? Was this a new expansion valve ?

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Saumil S. Patel

Yes the txv is new. This compressor is a reman. The line is cool to the touch but because of the air temp coming out I can't tell if I have too much freon or not enough. I can feel air blowing out through the grill under the wipers. I am not sure that the frash air door is not staying open all the time. This is my first MB so I am not sure what to expect from the AC system. I do not want to replace the evaporator unless it is necessary.

suggest that you remove the glovebox to see fresh air door.it needs to be pushed forward to close.i made a pce of two by four with a v cut in one side and was able to jam the door closed.try this first and see what diff it makes.to get to the coil face you will need to remove the blower motor and reach down through the duct with a brush[it can be done].

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

How much freon did you put in?

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William
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1987 420 SEL - Like a fine wine only better with age

Yes, use 80% of the R12 spec when substituting R134a.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280