My AC compressor with 170K on it makes Ice Cold air
(1) It has a Belt that squeals like hell when the AC in operation. I even drained the system and added 6 oz ester oil and the squealing persists.
(2) The Clutch takes high current to operate. (The clutch by the way is new.) I have to hook it to the battery to make the clutch engage when the engine is in operation; the climate control signal has 12 Volts but won’t operate the clutch.
(3) The compressor can be turned by hand when uncharged easily.

I believe the Air Compressor is dead. I just don’t understand why it can actually still make cold air…

What is wrong with my AC Compressor…it squeals like H_ll!

How tight is your belt?
Is there oil/other contaimantes on it?
Is there oil/etc. on the pullies?

My belt squealed and I had to get it pretty tight not to make noise.
My Compressor sounds like crap at idle but it works okay...I think a bearing is going out on the pump...

Might try replacing the belt and cleaning the pullies with brake cleaner..

Is there a way to test the condition of a compressor without wasting refrigerant?

My SD has a leak in the condensor since I picked the car up. I don't really want to waste freon if the comp is dead/dying.

+12 volts to the clutch for a breif moment ran the comp with no unusual noise.

Never looked but will the '85 380SE comp fit the 82 300SD? The SE was blowing 40F air prior to the crash.

The clutch is not powered directly by the climate control unit. The ACC energizes a relay, which powers the clutch through the low-pressure cut-out switch on the receiver/dryer. The culprit is likely the relay or low pressure switch.