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Old 07-05-2001, 06:56 AM
Posts: n/a
I've been having a problem with the A/C in my 98 C230 (28,000 miles). The compressor cuts out anywhere from 1 to 5 minutes after the car is started. I first noticed the problem two weeks ago on a trip to central CA for a wedding. The A/C was running fine up to the point where we stopped for lunch. It was blazing hot outside (108 to 110) and the car sat in the sun for about 1 hour. It's black with black leather, which compounded the problem. When we returned to the car the temp gauge on the dash read 120. I'm not sure but I believe that may be where the temp gauge is maxed. After driving the car for several minutes the A/C went out and hasn't functioned normally since. To say the least it wasn't a pleasant drive. The A/C would work off and on the following week but this week it will not run at all, at least for no more than a few minutes. The compressor runs fine (hard and cold) for the brief period following ignition. I'm sure some safety feature is cutting off the compressor, for some reason. I've checked the fuses and looked over the compressor, belt and A/C system and see nothing out of the ordinary.

I've done several searches for related posts and read dozens related to A/C and related topics. One interesting article by Steve Brotherton I came across mentioned something similar with the C230.

"I first ran across these tests while trying to solve a C230 problem whereby its compressor would shut off within one minute of starting. There were some fault codes involved with communication between the fan control module and the pushbutton module. I came across the actual value test while trying to make some sense of the code. I tried the actual values without the engine running. The evaporator temperature showed 155 degrees. When I discovered that the dealer had two of the sensors in stock, I had a good idea that the problem had been found"

This is interesting because (Using the code function threw the climate control LCD) I saw Evaporator Temperature at 145 (function 5, if I'm not mistaken). This while the engine wasn't even running and hadn't been running for hours (temp in my garage was about 75). After starting the engine the compressor kicked in and the evaporator temp still showed 145 to 150. Then out of nowhere it began to drop. It instantly went from 150 to 80 then 40. Moments later it began to go back and forth from 50 to 150, like it was possessed. The compressor then disengaged. The other reading (again using the code function) seemed normal. Refrigerant pressure (code 7) was 4 when the car was shut off and 14.6 while running. Refrigerant temperature (code 8) was 91 with the engine off and 120 on.

I also read in the "Do it yourself" section that this could be caused by a bad belt or by the belt tension being off. What is the likely cause? I'm leaning towards a bad Evaporator temp sensor (given the strange readings). But I'd like to go in to see my mechanic with as much info as possible. Or better yet knowing exactly what the problem is.

Any input would be appreciated. Even if only to tell me that I'm dead wrong and to take the car to somebody who knows what they're doing

Sorry for the length of the post. I figure others with a post W202 might be interested if they come across a similar problem.
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