2000 Cherokee Classic AC Problem
 

I'm desperately trying not to have to take the jeep into the shop but here's what's going on and what we've already looked into...

The AC only works intermittently and does not work far more often than it does work. It appears that the message is not always getting to the AC clutch telling it when to engage. Air still blows when the AC clutch isn't engaging, it's just not cold.

Checked:
AC Relay - Good
AC fuse - Good
Freon - full pressure
High and low pressure switches - both getting 12v and appear to be functional
A/C clutch feed - registered 8v

Does anyone have any other idea of what I could check or what might be the problem?

How'd you verify your pressure? Did you look at both the high and low side readings?

I used the gauge that came with my Quest brand Synthetic AC Booster. We got the AC clutch to engage one time (out of dozens of tries), checked the pressure on the low-side, and added refrigerant until the pressure was about 50-55 PSI (Temps are ~100 outside today).

Does that help narrow it down?

You're just checking the low pressure side and that doesn't tell the whole story. I'm a die hard do it myself person, but there are things that should be done by a qualified shop (or a do-it yourslef type with proper training) and AC is one of them. AC systems should be evacuated and refilled when problems like this occur after a proper diagnosis. Good luck.

Too much or too little pressure will make the clucth work irratically like on/off/on/off I m quite sure of this.I think Robertj has the right idea in this case to have a shop empty it than refill for you if there are no leaks etc you should be fine.

like the others have stated, a/c can be a pita. i am certified and what you showed for low side psi is correct but the high side can cut you off as well. just like the low pressure switch, there is a high pressure cut off switch. if your not sure, perhaps its best if some one else checks it over.

what was the result of your AC problem?? I'm having the same issues.

Does the auxiliary cooling fan behind the radiator turn on when you start the AC? If not, your AC could be overheating and shutting down as a result.

2000 XJ with COLD A/C
 

It is the step by step that gets the correct answer.
Battery-15 amp #10 fuse on kick panel-Fan Relay-Clutch relay-Low Switch-High Switch-Temp switch on water outlet-Aux Fan.
Everything has to work together or the system will be twitchy.

It seems for many the High Side binary switch was the culprit-pressure/heat builds and the compressor clicks off. Mine started with the bad aux fan motor.

I popped my fuse when i was diagnosing the circuits. Did not find it til week week later! Ice cold now. Nothing like an XJ with A/C.