My AC R12 was working perfectly until the compressor decided to get noisy. I decided that this was the time to revamp the system. So I said a sad goodbye to my very cold R12 system. I replaced the compressor with a good used one I had, the High and Low pressure hoses with new ones that have the R134 fittings, Replaced the expansion valve and dryer. Replaced all seals with the R134 seals (green). Using compressed air I blew out as much of the old oil from the system as I could. This will be replaced with 10 ounces of PAG oil. so all is well, SOMEWHAT.
THE BAD NEWS> (LONG WINDED)
Not wanting to engage the compressor, with the engine running, since I had no oil in the compressor. I wanted to verify that the AC clutch on the replacement compressor was working. Before I get to the issue at hand, the PO had patched in a wire from the positive feed of the AC (green/brown) to the Aux Fan. NO FAN RELAY. When the AC was turned on, both the AC clutch and the fan would engage. I had left the patch wire for the fan disconnected and i turned the key 'on' turned the AC blower on and the clutch engaged. Somehow the patch wire for the fan shorted out and the AC clutch stop engaging. The fuse at Terminal 13 on the passenger side fuse box is good but now I have no power to the AC clutch connector. Where is AC relay located and is there an inline fuse somewhere between Terminal 13 and the AC clutch. The blower motor works, the flaps move on command. Only problem is the power supply to the AC clutch.

 

You mean there's no fan relay in the car?



OK




Good. That's what's supposed to happen



But you just said ^^^ that it DID engage

Oh, never mind. I get it now. it engaged and then the wire shorted...and now it won't engage





There is no compressor relay if that's what you mean




The system uses an inline fuse that's clipped to the right side of the heater case behind the right side console "cheek panel".

There's also a "thermal limiter fuse" clipped to the a/c compressor mounting bracket. It blows if the freon level is low. Do you have this on your car or did a PO work around it?

Cheers
DD

 

There are also two a/c fuses in the fuse boxes. Can't remember the numbers off-hand. Sound like you found only one of them

cheers
DD

 

Thanks Doug. Yes, the PO just patched in a wire to the positive of the AC plug and plugged it into the feed terminal of the relay connector. No relay. I will be correcting that. The thermal limiter fuse was also bypassed. No where in sight. I can live with that. Using my DVOM, the green/brown feed wire to the AC clutch patches somewhere in the harness and becomes white/black. This wire goes to the big connector and goes into the passenger side of the car. At that point I lose the wire, I don't know if it changes color again. Tomorrow I am going to Radio Shack to purchase a pin to pierce the insulation on the wire harness inside the car to try to locate this wire. I am trying not to dismantle the car too much as I recently put it all back together.

See attached photos. 1 and 7 show the wire that goes to the AC clutch. White/black. 2 and 3 show the fan relay connector and the patch wire that was used. 4 and 5 I guess is the inline fuse you are talking about.

 

Yes on the inline fuse pic.

As for the rest.....

It's hard figuring out what someone else has cobbled together.

I'd go back to square one and return everything to original configuration. Go to the "How To" link at the top of this section and open the "S57" wiring diagram. Scroll to section 25.1

Don't scroll too far or you'll end up in the "XJS" book and things will really get confused :0

Cheers
DD

 

GRRRRR!!!

I was going to say "get rid of that red clip on". They cause more trouble than the famed Carter and his liver pills.

But, Doug went one better. Cut it all out and rewire to stock with proper connectors and soldered and shrink tubed splices if necessary.

Oh, the probe you are looking for is in miladie's sewing basket. A largish needle or a safety pin. Just add a wire and a lamp and you are in business.

Not the best procedure, but often done. The problem is pierced insulation. A dab of liquid tape would ameliorate the issue.

Carl