1990 300 Sel A/c Problem
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1990 300 Sel A/c Problem
Hey guys...I just became the owner of a nice 300 SEL that I bought from a co-worker. It was one of those " to good to pass up" kind of deals. Anyway...the car had a few small issues that I fixed, then took it to the car wash to clean up the engine compartment. Since then I've been having a problem with the A/C. I've heard this model is notorious for A/C problems. I'm not sure the car wash caused the problem or if its just a coincidence. But I can't get the compressor to stay on. If I put the A/C on auto it will cool for a few minutes then the compressor shuts off and won't come back on until the car is shutoff and restarted. Sometimes it will stay on if I use the manual fan buttons and don't press the auto button at all. Sometimes that only works for a short time but then sometimes it will work all day. It will freeze you out when the compressor will cooperate and it seems to allow me to adjust the temperature. While running in manual mode the compressor will cycle also. Anyone else ever have this problem or know where I should start looking?
Thanks,
Dan
Thanks,
Dan
Thread Starter
Newbie
Joined: Mar 2006
Posts: 5
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A/C problem
Update.....after doing a little more research I discovered an article about A/C diagnosis. Turns out my compressor was shutting off when the belt slipped. I didn't realize there was an rpm sensor on the compressor that shut it down when the rpm doesn't match the motor. The reason the belt was slipping was an overcharge on the system and/or a worn belt. I hooked my gauges to the system and it looked to be overcharged. I released a little freon and things returned to normal. I still need to replace the belt. It looks pretty old and I still get a slight slippage under acceleration when the transmission downshifts. Sometimes it causes the compressor to shutdown and sometimes it doesn't. Anyway...so far so good.
MBWorld Fanatic!
Joined: Jun 2003
Posts: 1,054
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From: Nashville
300SEL
my only a/c work has been to replace the suction hose. pretty expensive part, $650 on the internet and over a thousand from the dealer. needless to say, i bought it off the net and installed it myself.
