AC compressor engages and disengages at random, will not stay engaged or cool.

What is your question?

As I said the coil will not stay engaged on the AC compressor, it started doing it without any warning. Everything of interest in troubleshooting the problem has been done including pressure testing, replacing pres. switch, relay, fuses, control module on the dash, etc. I disconnected the battery and it did great for about two hours then started doing the same thing. It has my mechanic completely stumped.