I've got a 2000 Jeep Cherokee Classic.

My compressor will disengage after running strong for about 15-20 minutes; then will not rengage till the vehicle has been sitting for ~3-6 hours (havn't really nailed down the "reset" time). I have R-134a, I just had a mechanic service / top off the coolant and there was no change in the performance. He said when the compressor was running the high and low side were reading good pressures and the AC was kicking out 55 degree air.

This mechanic suggested that I replace the compressor, some lines and the expansion valve....thats when i walked out.

I feel like its an electric issue like a control/sensor/relay, or maybe water is in the coolant that's freezing up and clogging the lines and taking a few hours to thaw out to unclog.

Any suggestions on how i can rule out a control issue, or how to further diagnose this?

 

If you are reading good pressures when running, then don't mess with the expansion valve. They either work or they don't. The compressor seems to work as it should if the pressures are good. I agree that the first thing to check is an electrical issue.