I am having a random issue with the A/C compressor not turning on. Some days it will not run other days it runs like it should. The blower in the truck works fine. Everything is stock. One day I went to the store and it did not work on the way there. Half way back home it started blowing cold air. It looks like the clutch is not getting power to engage.

It would not come on yesterday. It is a very random issue that does not seem to have any pattern. I reached down and pulled on the wire going to the compressor and it did nothing.

Has anyone else had this issue? If so how did you fix it?

Thanks,

Grant

 

I thing, don't pull on the ac clutch wire.I did and it broke off at the ac clutch, effectively causing me to have to pull the compressor. It could be a problem with the cycling switch.Here is a recent thread on this:

https://www.dieseltruckresource.com/...e-vent-330744/ Good luck...Mark

 

Fill out your sig or tell us what exactly you are working on.

 

Thanks for the quick reply. I did not pull on the wire with much force! I will check the cycling switch. After reading about it it does seem to fit the problem.

 

I don't know a whole lot about the intercooled trucks, but I think that there is a PCM (aka the brain) and a CPS, crank position sensor, that may play a role in the ac.The gurus should chime in soon, they are probably busy converting an RC with a 6bt...Mark

 

The PCM doesn't control the non-relayed AC system on a 91.5, nor is there a CPS for that crossover year.

 

Thanks for the info, that is why I said may and that I don't know much about that truck. I also still don't put water in antifreeze, you can pass that on...Mark

 

I started having the same problem just a few days ago. If I keep switching it off and on, it eventually engages. Or, if I just let it blow for a while, it wakes up. I'm suspecting the switch on the dash may be at fault.
I haven't had time to investigate yet but I bypassed my cycling switch back when I did the Jim Lane blower relay upgrade. So, I doubt that's it.
If I figure something out this weekend, I'll report back.

-Niemand

 

Same here! Nothing but 200 proof!

 

Yeah, he knows what I am referring to, the fun fest that he and a former member had at my expense in my renew your a/c thread, I don't like to be trolled...Mark

 

Found it.
It was the Wide Open Throttle relay on mine. It's the one on the fender, closest to the hood's hinge spring.
Hope it's that easy of a fix for you.

-Niemand

 

Wide open throttle relay? What is that and what does it do? How did you determine it was the problem?

 

 

So it seems the a/c has 100% quit now. I found the cycling switch near the passenger side fire wall. It looks like the probe wire goes to a relay which is wired to the a/c clutch with a blue and brown wire. There is also a blue wire with a white strip. Not sure what it does or where it goes as it does not go to the clutch.

I unplugged the connector from the clutch pig tail and checked the voltage. It was getting 11.5 volts with the a/c on and 0 with it off. I plugged it back in and it did not work. I sprayed contact cleaner on the plugs with no luck.

Next I tried running jumper wires to the clutch pig tail to my battery. That worked! The compressor came on and cooled like it should. It would kick in and off with no problems with me touching the wire on and off the battery. Actually it cooled better than ever with me controlling it.

I read there is a temperature switch that can be mounted on the evaporator coil to control the compressor. Does anyone know where to get this switch?

 

What you could do is run the wire through a fuse and maybe a relay and to a switch on to positive inside the cab, as a temporary basis, until you figure out a more permanent solution...Mark