Guys, I am having my AC go crazy. I have a feeling its the Compressor clutch not engaging for some reason. Anywho... this is the problem... If I were to let the car sit overnight or 8 hours like I do when I leave work the AC will start up fine, but if I were to turn off the AC on the dash it will not come back on, and I do not hear the clutch engaging. And once the car has been warmed and you try to get the AC back most of the time i still do not hear the clutch engaging?

On top of it I took it to a shop and they checked it out and said the pressures are good, compressor is fine, and they could not replicate it, any ideas guys?