A/C Compressor not engaging

[fastass350]

I've filled the truck with 134, there's power going through the pressure switch, and power on one wire at the compressor, ground at the other, and the clutch won't engage. Is this something I can maybe fix without evac'ing the system and starting over? I assume I can pull the clutch off the front??

This is on my 85 btw

Thanks.
Chris

 

[franklin2]

Take a feeler gauge and check the gap on the clutch. Low end is around .014 and the high end is something like .030 or .040. Mine was way over .040, and it would work once in awhile. I went to Autozone and rented a special puller to pull the clutch off. There were too shims behind. I took one out, and put it back together. That put me on the low end of the spec, a little too close really, but it works ok and it fixed the problem.

 

[Compu Doc]

Did you try jumping the low pressure switch to see if the clutch came on?

 

[franklin2]

I think he said there was power going through the switch to the clutch.

Also on a site where I was reading up on this when I had the same problem, the guy suggested taking a broom handle and helping the clutch engage as a test. It looks a little scary with everything whizzing around with the engine running, but sure enough, a little bump from a piece of wood while it was turning and it popped right in and started turning the compressor.

 

[fastass350]

Yes, power is through the pressure switch, to the compressor. I can manually engage it (with a piece of wood when running...or having the key on, and pushing the clutch in by hand, then starting) and it'll stay running. So I'm concluding that it's the air gap in the clutch. I'll start it manually for now, since I don't drive it much, then tear into it. Any great suggestions to removing the nut on the shaft? Like how to hold everything still to get the nut loose? Also, is it right hand or left hand thread?

Thanks for the help

Chris

 

[RLDSL]

Before you do surgery on the compressor, take and make a jumper wire and attach it to one of the compressor mounting bolts and the other end to the battery ground. Sometimes compressors will have a weak grounding issue that will cause them to have trouble firing and running a jump wire will take care of it.

 

[franklin2]

Get a ratchet and socket on the nut, and then smack the handle of the ratchet with a hammer or something to break it loose. And air impact works well, I don't remember it being left hand thread. You have to get the tool to get the clutch off though. Advance auto will rent you a complete clutch tool set. I am tempted to go ahead and buy that thing, since I had to rent it to get the clutch off and back on a GM r4 compressor. They will take $100 from you for that set though. I believe the Autozone tool was $20, and they did have the correct one for the Ford.