Why will the AC not come on in a 1996 Cadillac Deville replaced the compressor the accumulator and the orafice the compressor is fully charged with freon?

Redoing an AC system is trick business, the system must first be evacuated by a vacuum pump to remove all air before the refrigerant can go in and the pressure switch will not allow the compressor to come on or it will short cycle.

Assuming you did it all properly try disconnecting the wire to the compressor and jumping it to 12 volts, that will activate the clutch. If it comes on and blows cold then the switch inside the car might be bad or some other electrical issue such as relay or fuse is the problem.