Just wanted to post an additional comment as a thank you to the author of this thread and to make a contribution to the forum.
Last week, my AC stopped working (2006 CRD). Popped the hood, couldn't hear the clutch engaging...could barely see it since the darn compressor is at the bottom left side of the engine. Wasn't moving. Checked fuse, all good. Checked relay by trading it with another, that was good too.
Took it to my AC/radiator shop who re-charged my freon last year and he confirmed there was no power getting to the compressor. My first knee-jerk reaction or fear was a failing compressor. He said that he thought the compressor could be fine but that something was interrupting power to the compressor..so he said "take it to an electrician before you take it to a shop for a new compressor".
LOSTJEEPS to the rescue. Took it home and logged on before taking it to the shop. Did an "AC no working" search and landed here.
After reading CMSRock's very accurate description, went out to look under the hood to identify parts. Pressure switch is relatively easy to get to. Pulled the plug and did a continuity test...no beep....switch open. This part was a little tough since the two electrical terminals are hard to get to.
Logged onto O'Reilly and searched for the part.
https://www.oreillyauto.com/search?q=MRY+20922Climate control 2 terminal pressure switch
Picked up part and decided to try removing without tools. Surprise, didn't need any. Unscrewed it from the top of the accumulator (aluminum can on right firewall). Heard a little pressure pop. Removed the old o-ring and installed the new o-ring that came in the box with the new part, then screwed on the new low pressure switch. Re-attached the plug and voila! Cold air again. Heard the clutch re-engaging.
Thank you CMSRock and LostJeeps admin.
steve