For the last year or so, my a/c has only worked intermittently. Today I decided to jumper the clutch on the compressor to make sure it locked up. It did. I removed the jumper and went about my business.

I managed to blow the a/c fuse during my testing of the clutch. I replaced it.

Now, oddly enough, the clutch locks up when I turn on the blower fan. Regardless of the A/C button. When I turn on the fan, the clutch locks up and stays locked up until I turn the fan off. It doesn't cycle on and off, like it should.

The A/C button still lights up, it just has no function now. Even when the fan is on, pushing the A/C button will not disengage the clutch.

WTF did I do?


I'm thinking I might have to put a relay on the clutch wire and cycle it on and off myself via switch.

 

320 kb
http://www.pnw4runners.com/index.php...e=AC_HEATE.PDF

See if that helps

 

a/c clutch is controlled by the something called and a/c amplifier board you may have blown something on this. if you want to replace this its behind the glove box on top of the evaporator.

 

Just for giggles, try popping out the AC button assembly and see if it still stays on.

 

I just popped it out.. The clutch still engages when the fan is turned on. This is so strange, it's almost comical.


Corey,
Thanks for the PDF. I've been staring at that wiring schematic... I'm even more confused now.

 

ooh, maybe the A/C amplifier board like thefallman said. Probably best to check all connections and maybe get one from donor vehicle pretty cheap from boneyard.

 

There is a relay looking thing on the A/C box in the cab, did you fry that?

 

For now, I unplugged the a/c amplifier. The blower fan is back to normal operation. I'll probably try to pick up a used amplifier from the junk yard. If that doesn't work, I guess it won't kill me to go another summer without a/c.

 

Sorry to hear that, you can probably get one very reasonable in bone yard. I was afraid it would be the amp, Definately worth getting just to beat the heat coming up soon.

Keep us posted.

 

If you can't find one at the bone yard, send me a pic I have a full A/C system from the 89 pickup I am parting. Not sure of compatibility

 

I would be interested in the A/C system components. I have a 1990 Extracab/3VZE, and a 89-95 V6 donor truck makes the best match for a retrofit, but some 22R parts work? Let me know what you have and what engine it went with, and maybe we can talk prices.

 

Alright, I put a new amplifier in today. The problem described above has been fixed. Unfortunately, my original problem of intermittent a/c still exists. I'm guessing it's a sticking expansion valve.

 

Possibly, seems there was a recall on those. Pretty sure mine was recalled. Not very good with AC, can't advise you there. If you had some pressure meters, you might narrow it down.

 

When is the last time you had the system charged (R12 or 134A whichever yours uses). While not reliable what does the sight glass look like when the system is running? You could be low on gas and the system is running like that to keep from burning up.

 

When the problem first started occurring, I added some 134a. It had no effect. At this point, the only thing I can think of is a malfunctioning pressure switch or the expansion valve.