Need some A/C advice!
Thread Starter
Newbie
Joined: Jan 2005
Posts: 14
Likes: 0
From: Geneva, AL
93 500 SEL
Need some A/C advice!
My air suddenly stopped blowing cold on my 93 500 SEL. Checked fuses, they're good. Then had my local mechanic recharge and add Super Seal Premium to system in case there were any leaks. He said compressor still wouldn't kick on, though it looks fairly new. He checked electrical (as best he could I suppose), and couldn't find any problems. Anybody encountered this before?
Thread Starter
Newbie
Joined: Jan 2005
Posts: 14
Likes: 0
From: Geneva, AL
93 500 SEL
More info on the problem --- compressor is not locked up or anything. It spins free, but it's not getting electricity. Fuses are good. Are there any inline fuses or relays that need to be checked?
Senior Member
Joined: Jun 2003
Posts: 302
Likes: 1
From: Salem, OR
08 Lexus GS350 AWD. 08 Lexus RX350 AWD - wife's. 94 MBZ E320 - still have it.
Sounds like a push-button control unit problem. I had similar problem with my '94 Mercedes. Same signs, no power in the AC compressor. The push-button control units on these car were very unreliable.
Super Member
Joined: Jun 2003
Posts: 713
Likes: 147
From: Aridzona
'15 S550, '10 E350 P1/P2, '02 ML320
It could also be the speed sensor built into the compressor is not sensing correct engine speed. This is usually caused by a slipping drive belt, but could also be a defective sensor. This sensor prevents the clutch from engaging when it detects its speed to be lower than relative engine RPMs.
Thread Starter
Newbie
Joined: Jan 2005
Posts: 14
Likes: 0
From: Geneva, AL
93 500 SEL
I did an in person consult with the MB indy who rebuilt my transmission. He mentioned the control module problem as being the probable culprit, but will diagnose it next week. BTW, though his shop stays full of European cars, he did say that MB's are "overengineered." The newer the Benz, he said, the more "overengineered" it is.
Thread Starter
Newbie
Joined: Jan 2005
Posts: 14
Likes: 0
From: Geneva, AL
93 500 SEL
Most likely culprit is the refrigerant pressure sensor, I've learned. Since the pressure in the system is good, it's not the evaporator. If this sensor is bad, it will keep the compressor from coming on and give you a readout of 00 on the indash codes. When I get the final repair, I'll update the forum.
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