I just replaced the compressor (a re-man), dryer and expansion valve on my '95 S320. We thoroughly vacuumed the system after cleaning with the proper solvent, recharged to just a bit less than 2.5 pounds of R134.
The problem is that the compressor turns on for about 10 seconds and then off for 2-3 minutes, the starts over for 10 seconds, off 2-3 minutes, etc. All the pressures are within the specified range. The compressor runs good when we hot-wire it directly (although it does not cool more than a 15 degree drop). I replaced the pressure sensor on the dryer and now have no diagnostic errors coming up. The belt tension seems OK, I sprayed some cleaner on the clutch, just in case. Any ideas?

maybe the evap temp sensor? It is getting too cold and the system shuts the compressor off to reduce possibility of freezing, what about the expansion valve? Just some thoughts.
B

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Brian W. Heitman

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Thanks, I'll take a look at them. Any idea where the evap tem sensor is?

Another thing that would be an easy check, some compressors have a speed sensor on the rear of them, this is to ensure that there is no drive loss due to clutch or belt slippage, if that speed sensor is malfunctioning or not connected properly it will let the compressor run a bit and when it senses the engine speed is not consistent with the compressor speed it will shut it down. Just another item to check, if it is a Nippo compressor it likely has one.
Brian

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Brian W. Heitman

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If you send me your email address bwheitman@comcast.net I will send you the testing and diagnostic procedure for that climate control system.
Brian

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I sprayed some cleaner on the clutch, just in case. Any ideas?
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Depending on the cleaner , you may now have a slipping clutch..which willshows up the same as a slipping belt.

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I do not know which archieves post you refer to, but the pressure sw [ high side pressure] jumping suggestion in the archieves
is probably from a 124 chassis type set up [ 2 wire pigtail].
You have a 3 wire combined sensor and this test does not apply to your set-up. I believe center ground is the test for 3 wires pressure sensor for fan circuit.. I will check schematic on that for verification when I find it....