I took my car into the local MB dealer. They said it is the MAS too. Also said that I need a A/C system tune up to R134. ($700). I think i'll call Cool-It. Problem is that it cools well and I've heard that the R134 is not that efficent. I need all the cooling power i can get. These dark brown wagons really heat up in the summer. Thanks for your help.

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Ian Read
90 300TE4MATIC (124)
79 300SD (116)

iread,

If I understood you correctly, there are no known freon leaks, it's just that the compressor is locked in most or all the time. It sounds like you already know that this is a control problem, not a refrigerant problem.

If there is no leak in the system, I wouldn't pay so much as fifteen cents to change it to R134. It sounds like it might be a slow day at your MB dealers service department. They're trying to produce some revenue.

It sounds like you and Benzmac determined the problem to be the MAS. It also sounds like this independent A/C shop which is highly reccomended is the way to go.

There are some really good Benz service departments around, but there are also some that are thinking more of producing revenue than they are thinking about SERVICING their valued customers.

I was in Calgary about three weeks ago and about a foot of snow blew in when I got there. It's hard to imagine worrying about the air conditioner. Of course, in you're case it's like you're trying to turn it off! Just teasing.

Good luck with it,


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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in
Mercedes automobiles

I wouldn't worry about losing capacity if you should convert to R-134 in the future. I personally converted an '84 300TD dark blue wagon to R-134 and have a '91 300TE wagon (also dark blue) that had already been converted. They both cool just fine here in Mississippi where the temperature and humidity hang around 95 in the summer. The conversion is more questionable on cars that have capillary tubes instead of expansion valves and undersized condensors. The trick (as usual) is to make sure whoever does it knows what they are doing as the R-12 uses mineral oil as lubricant and R-134 uses ester-based oil. This requires that you totally flush system to remove old oil.

DISCONNECT BLUE WIRE W/RED TRACER FROM LOW PRESSURE SWITCH ON REC/DRIER,IF COMPRESSOR CONTINUES TO RUN PROBLEM IS IN M.A.S. OR WIRE IS SHORTED TO GND ! IF PROBLEM STILL EXISTS IT ORIGINATES IN PUSHBUTTONASSY.




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M.F.