my a/c wont stay on on 1999 Cadillac DeVille

when i start the car to leave the a/c blows nice and cold but after about a mile the dash says low refrigerant and the a/c turns of.i can shut the car of and right back up again and again the a/c is strong and cold then shuts off again.theres no leaks.i used a sniffer and it didnt hit on any leaks.i drained the freon and put a new orifice tube and all new o-rings.when i put it on a vacume before recharging i let it sit with the vacume unplug for 35 minutes and it held a good vacume so i know theres no leaks.oh yea.just replaced the commpresser also.what am i missing?im thinking maybe the pressure switch is bad or maybe a broke wire.i dont know.i know im over it.should junk the stupid has the northstar engine.hate them things.

Asked by for the 1999 Cadillac DeVille
Take pressure readings with it running 'till it stops. If the pressures are right then it's likely just a bad pressure switch. If this all started after the AC repairs it's likely one of the parts replaced or the charge level is the cause, if it was already doing it then probably a faulty switch. If all else fails and this is going to make you want to junk it you could just hotwire the compressor.