Alright. Last year I posted about my Jeep having an AC issue. Me being the lazy bastard I am, I just said eh whatever I'll just go without AC for the summer. That was fine, but this summer I am moving to the promised land, the holy grail of all off-road vehicular action, Moab. I do not want to live down there without AC, and I have learned some new stuff that may be useful to anyone who is nice enough to assist me. So, here goes.


What I've done so far:

I have replaced the low pressure switch, as it was missing when I bought the jeep. I have tested every fuse and relay that relates to the AC system, as far as I know. They are all good. I have checked the clutch supply line with a VOM and it read 12V as expected. I just finished checking for a vacuum leak. There are none. I have jumped the compressor clutch via the low pressure switch, It engaged, so I don't think its seized. The compressor does not engage when I start the engine with the AC switched on. When I take a pressure reading on either side (HI or LO) I get a reading of 0psi. I assumed that this could be a vacuum issue but again, I just checked for a leak and couldn't find any. Is the most likely problem that I have a huge refrigerant leak somewhere, and when I recharge the system (which I have) It immediately leaks out, causing the compressor to stay off?


Any help is much appreciated. Thanks in advance.

 

You have high and low pressure switches to prevent the compressor from running when the pressures are out of a reasonable range. Obviously 0 psi is no good so your low pressure switch should be preventing it from running.

I would go to O'reillys and borrow their ac stuff to pull a good vacuum on your system (if it holds one) then dump the correct amount of refrigerant into it and see what happens.
It would make sense to find a big leak somewhere. Did you charge the system recently? Or did you charge it last year?
If it's actually a massive leak that comes out immediately I would think you'd be able to hear it right after trying to charge it.
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Be happy you have AC parts at least!
Mine is missing all the parts. No compressor, no condenser, no accumulator, lines are cut by the firewall... I'm basically stuck with rolling down the windows. :/ Good thing it's not my DD

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I charged it about a week ago, and when I finished I did hear something like a rush of air coming out of the vents. Could that mean my evaporator is shot? Also when I’ve charged it I’ve had to jump the lo pressure switch to get
the compressor to run so I’m not just pumping it into a closed system.

 

That rush of "air" must have been the refrigerant. So yeah you must have a nasty leak likely in the evaporator like you said if it's coming out of the vents.. Sorry to hear.
​​Not sure what you mean by "not pumping into a closed system" but jumping or not jumping the pressure switch has nothing to do with the fact that your refrigerant leaks.
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Oh well, thanks for the help, and I just meant that I did that so the compressor would stay on, that way the refrigerant would work through the system. Thanks again.