73-87 Chevy _ GMC Trucks > Electrical

Need help with correct electrical polarity for Harrison Compressor Clutch


Hello, I'm new to the site. I have a 1985 C20 that my dad bought new. He's 92 and recently gave it to me with 80k orig. miles on it. It has a 350 and factory A/C with a Harrison 434 compressor on the driver's side. I removed the compressor from the bracket to access the power steering pump below and when I did, I unplugged the two-wire harness to the compressor clutch. The two wires are a green wire and a black wire. The green wire must be power because the black wire has a ring terminal at the other end of it and goes to a ground on a stud near the alternator bracket. My problem is --now I'm putting it back together and I assumed the electrical connector would only plug into the compressor one way (I didn't pay any attention to the plug alignment when I disconnected it a few weeks ago). But the plastic is partially broken and I can fully seat the electrical connector either way on to the metal tabs (see photos). Looking at the compressor from the front of the truck when the compressor is bolted into the bracket - the connector is at the 11 o'clock position. I ohmed out both tabs to the compressor body thinking I could ID the ground tab that way but neither one ohmed out. Can anyone help me with which colored wire (green or black) should be on top? Thank you for reading this post.

Welcome from SoCal San Diego!

It really doesn't matter.

You are energizing a coil that produces magnetism.

In other words, it will work either way.

Congrats on the great gift!

Green is the +12v to engage the clutch the black is ground and is usually grounded near the compressor with a ring lug and bolt.


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