So along with all my other great luck recently, my a/c has decided to take a turn for the worst. It started with a squeaky belt on start up, figured at 200,000 miles I should get a new belt anyways. So later that day it started squeaking constantly and when I turned off the a/c it stopped. So fearing I would mess something up I left it turned off. Figured it might be low on refrigerant, so I picked up a bottle of the DIY stuff. Well it had over 100PSI in the system on the low side with the compressor on. So I leaked some out (I know I just killed the planet...) and once it got to the green section of the gauge ~40psi the squeaking went away, but then I noticed that the compressor was not cycling off. Then it started gaining pressure and got all the way back up to 100PSI. So I replaced the high pressure cut off switch but still the same thing, figured that sounded about right and was cheap.

So I obviously want to get this fixed without throwing too many parts at it. Any suggestions? Or any sort of diagnostics I can do? My next thinking was the compressor cycling switch.

 

If the pressure keeps going up to 100PSI I would check your fan clutch for correct operation. If you shut the truck off does it spin for a while?

40PSI isnt necessarily correct. Summer time I see anywhere between 35-60PSI with A/C temps where they should be. My compressor blew the front seal because my Efan controller wasnt kicking on for high condensor temps (high pressure).

Without buying a high and lowside gauge setup or seeing the truck in person its a little difficult to say. What you can do is let all the R134a out. Pull the orfice tube (if you know what that is) and check it for metal bits, if its full A/C compressor took a dump (which it may have but hard to say without high side reading). You can also try refilling it with the proper amount of R134a. The system calls for 34oz or 2lbs 2oz. I usually keep systems about 4oz below maximum for best temperature in cabin. So you can fill the truck with 30oz R134a and know it is at the proper amount despite whatever the gauge says.

The orfice tube is in the high side hose (smaller in diameter). It is located in the condenser-to-evaporator line at the condenser fitting.

I can look at it at the shop too on my lunch or on a weekend if you get to that point.

 

Well I could take it apart and check, if you think that is the best option. Or depending on when you can look at it over the weekend I could come by tomorrow or Sunday.

I admit that a/c is the one thing I know very little about, but that doesn't stop me from trying to learn and fix it.

 

Check the fan clutch (assuming you have a mechanical fan). See if it pulls a lot of air. If you shut the truck off how long after does it spin?

If it stops spinning after a second or two then its ok.

Otherwise I can check it tomorrow am sometime.

 

I have a mark viii electric fan. On a side note though, 2 weeks ago the fan literally melted and I had to drive it from Tempe to Maricopa with no fan, never got over 210 though, but when stopped no air was going through the condenser.

 

So, I replaced the compressor, accumulator, and Orifice tube. Had it evacuated and charged at a shop, held 28psi for 10 minutes. then after some driving around I noticed the compressor doesn't shut off still, even with it in the 60's at night. So I replaced the cycling switch on the accumulator, but when I did it leaked quite a bit of freon. So I figured it needed more it was at about 20psi and put 24oz(2 cans) in it to where the low side was about 25-30psi and still it stays on.

Where should I go from here? I figure the old compressor went bad because of this underlying problem of the compressor not shutting off, and don't want to destroy another compressor.