[Brian R.]

Pressure switch cuts off A/C compressor when internal pressure falls too low because of insufficient freon. If you are sure you have enough freon charged, then the pressure switch should have continuity (0 resistance). Check with ohmeter. It is on the receiver, a small can-shaped tank with a sight glass on top. Just follow the compressor lines. If the pressure switch has high resistance, then it is defective and needs to be replaced. If it is not fuctioning, then your system thinks you are low on freon, no matter how much you have in it.

If you replaced the A/C amplifier with others and it still didn't work, it is not likely to be the only problem. Check the other functions I mendioned first.

If you have to rely on a mechanic, I would bring it to the dealer and get it done right (if they are competent). See if you can find a competent dealer.