Unknown wire

CharlieL

Member
I’m restoring a 72 Buick Skylark and have a black wire coming off the rear of the AC compressor that has been cut off. I can only assume this wire should go to ground but don’t know. All wiring diagram’s don’t show this wire only the two that plug in on the front of the compressor. Can anyone help me out here?
 

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It's probably a replaced compressor most likely from a newer model.
This is the compressor wiring from my 67 Electra. Fairly simple a hot from the dash control and a ground that goes to the mounting bracket.
 

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the electrical diagrams may have the gauge and color of the wire. the a/c compressor in the electrical diagram will show where it grounds. The compressor would need to ground to the engine to operate if it only had one wire(ie battery grounds to engine). Somewhere there will be a star or textured nut washer to make that bare metal contact, because parts will be painted and reduce continuity. you need power and ground for compressor to work. if it works with one wire just a coincidence that it works, but not electrically sound for efficiency or performance in respect to if it grounds through the housing.
 
Charlie, there is a black wire on the rear of the compressor that connects to the superheat switch inside the compressor. The other end goes to terminal S on the thermal limiter. This is not a ground wire.

It shows up in the shop manual in chapter 13 in a few places. Attached are some pages that show it.
 

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Charlie, there is a black wire on the rear of the compressor that connects to the superheat switch inside the compressor. The other end goes to terminal S on the thermal limiter. This is not a ground wire.

It shows up in the shop manual in chapter 13 in a few places. Attached are some pages that show it.
Thanks great help 👏
 
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