Is the low speed fan coming on? Could be the red sensor on the drier. Is it no cold at all? That could be the blend door inside the unit. The doors and flaps are controlled by vacuum pods that could be going out on you also.

I am betting on the blend door if you say the compressor is engaging as that is normally the first thing that doesn't happen. If you were too high pressure in the system the compressor disengages, and if too low same thing.

Did you put in a new aftermarket radio lately? The vacuum hose for the center area is right behind the radio and A/C control.

Good luck hopefully gives you some ideas.