Use a an digital electrical test meter (you should own one anyway) Check easy stuff first-fuses. If Ok, then with key on a/c on, see if you have 11.5v or more at the wire terminal going to the compressor (unplug and check). If not check the PSI cycling switch at the accumulator. the switch is about 2 inches long, round about 1-1/4" diameter at the base and about the size of a dime where the electrical 2-wire terminal. Check for voltage there (unplug) -one of the two wire terminals in the plug should be 11.5v min.If you have voltage there get a paperclip and jump the wire terminals-clutch engage? if so cycling switch is probably bad. If NO power there-start looking backwards at inside a/c switch, relay at big fuse box under hood. Be careful. It would be good to buy a repair manual specific to your jeep ($25.00 or less online). Easy to follow the voltage flow from start to end (compressor).