On a 68 yes. Should have a grommet about 4" from end that passes through firewall. Do you have the 68 harness (green and yellow wires) or 67 (green and purple)?

 

Think it's a black wire. Only one shown going from compressor to firewall.

 

I have a 68 harness but there is only one wire left over after all of the other labelled wires were attached. The parts car did not have a compressor on it when I got it so I did not label that wire. It does have the grommet on it which led me to believe it was the correct wire. I didn't look close enough to see if it was solid green or green with a yellow stripe. It does not look long enough to reach all the way to the compressor though.

Since I have your attention.... how about the tach.
On the back of my tach it had the black ground wire and the red feed wire. The black wire from the tach had a 3" red pigtail plugged into it with yet another black 6" pigtail with a ground grommet on the end, all of it original to the donor car. The red feed wire had just a male plug end on it. The red wire that I assumed was the tach wire also has a male plug end on it. Do I have my wires mixed up, or is there supposed to be another short connector wire with a female connection on each end??

 

Dusty. Get a schematic-have the Pro Products enlarged wiring diagram. Clearly shown, the wire from the compressor through firewall is black. It has been black from 65-68's that I have owned/sold- worked on.The compressor would have a male end(black) and the longer wire(black) has a female end.It goes to the A/C thermostat switch. I have the black wire coiled up along with the auxiiialry harness green/yellow. Both the green and the yellow do not go into the engine cmpt.

It's late, but in the AM you might check with Slim as he has a 68 with AC since new in his car.

 

Think it's a black wire. Only one shown going from compressor to firewall.

The black lead goes from the green lead @ firewall to clutch.

 

Both the green and the yellow do not go into the engine cmpt.

That is incorrect for 68, the green does.

 

Typically there is the pink male and red female(usually a double bullet) that just connect to the appropriate tach wires. I usually see one, sometimes two, 3" pigtails that increase the range of the red wire but don't recall a black ground. The pigtails shouldn't change the orientation of the wires. The AC harness uses a black ground that goes to the wiper motor support bracket (same area) to account for the fan wiring change because of AC.

 

At the firewall on my '68 there's a green wire with a female connector, the wire comes out about 3" and has a grommet at the firewall. There's a black jumper wire plugged into the green one the other end of the black wire connects to the compressor clutch. To further confound the issue the clutch has a pigtail wire, hard to tell the color, looks sorta brown or tan. That pitail is about a foot long, the black jumper connects to the pigtail :crazy: