M1152A1 - AC compressor not engaging?

[matt2491]

I did some searching and reading but am not quite sure where to start.

New (to me) M1152A1 with factory AC. Heat works fine. When I flip the switch to AC, nothing happens. Looking at the compressor, it doesn't physically engage. Of course, the seller said the AC worked. If that's true, then it might be something simple, as opposed to something major like missing parts entirely. Everything else on the truck works great, so I doubt it's missing anything.

I know very little about how AC works so any advice on where to start would be appreciated!

 

[FlameRed]

I am a newbie, but I can provide you general guidance.

There is usually a low refrigerant pressure switch which is usually near or on the receiver dryer. Without sufficient R134 charge, it will stop the compressor from engaging to prevent the compressor from burning out.

The proper procedure is to put a set of AC gauges and see the charge status. If it is empty, then you got a major leak. If it is low, then you might have a minor leak.

Most auto parts stores will loan you a set of AC gauges for free, but they are not so expensive these days so you might want to look at getting a set. That being said, AC work requires a bunch of tools like a good vacuum pump, maybe a leak detector, and a few other things. However, one successful repair will pay for them all. But as you said, there is lots of specialized knowledge required also so you might want to find someone willing to look at it for you and at least diagnose it.

 

[matt2491]

Thanks for the info! Really helpful. I'll watch some videos on how to use AC gauges and see if that's something I want to tackle myself or hire out.