I have a 2001 Jeep Grand Cherokee 4.0L and my AC quit working. I thought it was the compressor clutch plate so I fixed the spacer on it and still nothing. Started checking continuity through AC Clutch relay in fuse box and found out I was not getting a signal from the side connected to the PCM to tell it to come on. Got a wiring diagram and found out there is a PCM Clutch relay control. I do not know what the PCM checks for before kicking the relay on. I have jumpered the relay and the compressor kicks on and AC works. If it helps, I replaced the water pump and t-stat about 2 weeks prior to this happening. Also, I have noticed that as soon as you turn on the switch for the AC (compressor still doesnt run but the car acts like it is on), the aux. fan kicks on, even if the car temp is below 110. Usually it doesn't kick on until the car gets to 210. Any help?
Here's the kicker, hooked it up to an OBD tool and no codes came back...Think I have Gremlins in this thing!