1999 Buick Regal AC problem

Bought this car new, has 140,000 on it, ac quit and took it to a trusted and competent shop, they said it appeared the compressor was bad, so i put in a new compressor, accumulator and orifice myself, had it charged up and worked good for rest of the day, then the next day it is just like before, the compressor doesn't click on, checked all relays and fuses, seems like an intermittent electrical problem, but where do i look for an answer???? HELP..Tom

unfortunately, you need to sit down with a wiring diagram and trace the power, thats the only way to diagnose electrical problems.

If its a climate-control system, then the computer is involved, which complicates things, and makes it much harder to diagnose.

One common problem is intermittantly bad contacts in the relays. If you haven't tried it already, swap out a relay from something else that uses the same relay (such as the horn relay)

If you have a leak you could have lost all of your freon.

bypassing the low pressure switch would activate the AC in that case (assuming its a standard 2 wire)

that would be a huge leak, and the person that charged the system should have seen it when vacuuming it down, I would hope!