If it's not cycling, as in clutch isn't activating, it isn't getting power to it. That can be due to many potential issues that involve wiring issues or pressure switch, as well as low content pressure.
When you turn the AC on, is the compressor clutch activating and spinning with pulley? Otherwise, if you unplug the pressure switch on the drier and add a jumper wire across both terminals it bypasses the switch and will let you test if there's power getting through to the compressor. If so, this only tells you one of two things, you have a faulty pressure switch, or the pressure is so low that it is operating correctly. Remove jumper wire after testing, not for AC use.
