I have the all too common ac problem where it blows semi-cold air and warm air intermittenly (cycling compressor). So, common knowlege from this board told me to purchase a recharge kit and read the pressures first. With car parked and a/c blowing full, pressure read around 20 psi. However, the compressor remained on the entire time and didn't cycle as it had been on the road. When I turn the a/c off to shut off the compressor, the reading goes to 100 psi.

Questions...what pressures should I see, and what is the proper operation of the compressor.

Sorry for the overkill on this subject.