Air Conditioning Help...85 GMC

[chargedstang89]

Hello all....I'm kinda new here, so any help would be great. The A/C system in my 85 sierra is complete trash. I want to replace it, but I cannot find the wiring that should go to the compressor. The guy I bought the truck from was a moron. The wires hooking the accumulator and evaporator are there. I traced them last night, and they go into a wiring harness type thing that runs across the back side of the firewall. It ends almost in the middle of the firewall, and there is a flat, kind of square plug at the end of those wires. I'm thinking that there should be a wire that plugs into that and then goes to the compressor, but I'm not sure. The Chilton's manual doesn't show anything about the A/C, so I'm at a loss. Can anyone help???? If anyone could post pics of the wires, that would be awesome. Thanks...Josh