Air conditioner compressor clutch question

I have 92 300SL. The clutch on the A/C compressor suddendly stopped engaging. The compressor freewheels. Air was cold until this happened. I checked the fuse and it is OK. Any ideas what to check next? If it's the
clutch, how hard is that to repair?
Thanks, Steve
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Have the freon charge checked first. Low pressure cut out switch keeps the compressor from engaging when freon charge is low.

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You can jumper the low pressure cut-out switch and test the compressor clutch to be certain your problem is low freon. Since the car is a '92, low freon is the likely problem. Hopefully you can just add a pound every summer and that will get you by.

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Thanks for the information. Is jumpering the switch an easy proposition? Any directions on how to do this?
Thanks, Steve

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CAVEAT!!! I am only familiar with my '86 420SEL so don't bank on what I tell you.
Facing the front of the car, hood up, look to the right front side of the engine compartment, a little behind the radiator and to the right of the radiator. You should see the receiver/dryer "bottle" with a small circular piece of glass in the top (sight glass). Somewhere, very close if not attached to the bottle, will be a switch with electrical leads connected via a plug. Unplug the plug creating its two halves. Take a piece of 12 gauge single strand copper wire, like household romex, and make a "U" shaped jumper. Now, holding the plug half that's NOT FROM THE SWITCH, insert each side of the U into the two female recepticals of the plug. You should now be simulating a closed pressure switch signaling adequate freon pressure. Therefore, the clutch should engage. You do this at your own risk as I am not a mechanic but only a mechanical engineer.

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Before attacking the A/C clutch you ought to ensure it's getting power. There are usually some safety block outs to protect the compressor - low refrigerant being the one I'd first check of jump for brief test purpose only.
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