OK, I'm trying to get the AC working on my 69 GS400. I'm having a power issue. I've got TWO wires of the same color (dark green) at the compressor, with different connectors (one matches the plug on the compressor, the other does not). One has power all the time, the other none of the time, both regardless of the dash switch position. The one that matches the compressor plug is the one that gets no power. But, it has continuity all the way to where it goes through the firewall. I can't figure out where the second green wire is supposed to connect. The strange part is, the two green wires seem to be connected, as they disappear into the wiring harness next to each other, but only one comes out the other end, and I get continuity through BOTH wires back through the single wire where it goes through the firewall. Yet, one has power and one does not. I'm still trying to wrap my brain around that one. Needless to say, the AC does not work because the compressor won't cycle. I'm thinking maybe the dash switch is bad. Any other suggestions?
Check to see if compressor works when you jump power to it. If it does, then check to see if you might have a small micro switch that connects to the fan switch lever. Sometimes the micro switch gets out of position and will not make contact to turn on the compressor.
the only one I have is actaulyl for my CHevelle, but they are pretty close to each other. It doesn't have the AC harness on it, so I have to go by the assembly manual, which has an AC diagram. The second wire is not on it :sad:
Andy, Is there a domino sized little "box" in the wiring harness anywhere near your compressor? If so, it's a thermal fuse that blows when the refrigerant charge gets low. I don't recall which GM cars had them, but 69..70..71..72...ish sounds right. Your other wire would go to a Superheat switch on the rear of the compressor. I kinda recall that being a just a "Chevy thing", but my memory is foggy. I'm thinking there was a BOP (Non-Chevy ) system where the superheat switch was connected to the compressor B+ line. If the superheat switch closed due to low refrigerant, it would blow the AC fuse in the fuse box. If both wires are green, unwrap the compressor harness back a ways and see if they are connected together by an inline splice. One may have burned/corroded off.
Hi all, just an update. I traced the fault to somewhere between the AC compressor switch in the dash and the compressor itself. I jumped the compressor so that it ran whenever the fan was on, and the AC works. According to the wring diagram there is no thermal switch between the dash and the compressor, so it looks like the wire is broken.
Don't forget your local library. Most have a pretty decent automotive section, with the Professional Chilton's and Motor's Manuals. Even for older stuff.
