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1992 400SE Air Condition question

1249 Views 2 Replies 3 Participants Last post by  JFKennedy
Apologies in advance, if this has been discussed here before as I could not find any.

The AC in my 1992 400se last week stopped cooling suddenly. The air blows like outside air, which in Texas that’s hot. I was on my lunch break so I stopped at a local shop, and he said there is no leak and it’s full of freeon. He said it’s probably electrical. I got in the car and suddenly everything was fine again until today again it went bad. I checked all fuses front and back. I’m on a fixed budget and want to see if you all knew anything that I could do before going to the dealer. BTW the entire AC system was changed about 2 years ago. ($2800.00)

Thank you,
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· Registered
92 500SEL to 01 E320T current 2014 lexus LS460
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3,885 Posts
140 AC

There are a few sensors that shut down the compressor, or the electric clutch could be bad. Here is something to check, when it shuts down were you accelerating hard? I had a problem where the fan belt would slip and the compressor shuts down, you have to turn off the ignition and start it again, AC comes on!
The tensioner on the belt goes bad, and sometimes when I go thru deep water it happens. I have replaced the tensioner, so it rarely happens any more. Try this web page there are some diagnostics
http://pages.prodigy.net/jforgione/MB_S500.html
 

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300 SE
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27 Posts
AC

I just got my AC repaired. There are several things that can cause the problem. One is the wiring harness which connects to the temp sender switch, that can cause failure. The wiring harness gets brittle and breaks causing shorts. The sender it self can be bad, and the RPM sensor on the compressor could be malfunctioning, mine happened to be a bad wire to the RPM sensor.

I mention all of the above because that is what I had to have replaced or repaired.

The wiring harness goes to the fuel injectors as well to some other parts of the car. MB wants about $1300.00 for this alone installed. The part cost about $575.00 and is of course is a dealer item. I installed it myself in about 1.5 hours.

After making this repair I took the car to Benzin Motor Works in Tulsa and they repaired the other items that I mentioned above for $213.00.
Total cost to be in the cool.....$788.00.
If there is anything else I can offer in the way of help, let me know.
 
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