If your system is low on freon or was low then the computer will disable the A/C Compressor. You will need to clear all of the trouble codes. See the stickys. Or disconnect the battery for 2 or 3 mins. Resetting via computer is a better option.
With my '93, after the system has been switched off for low system pressure, I need to bring the engine RPM up over 1500 and going possibly as high as 2500 RPM to get the clutch to engage. *shrug* Even my mechanic couldn't figure it out and recommended the dealer when he managed to charge the system, then couldn't get the A/C to blow cold. It took the recommended 2.2 lbs, yet it wouldn't go. It was my getting on it to pass a car that got the compressor to kick in.