David is the AC guy, it appears. I agree with him that the pressure seems low, and this can keep the compressor from coming on. You have to engage the system, turn the AC on, then go to the front of the car and watch the compressor. The outer section turns due to the belt drive, the center section turns on and off because an electric clutch is energized and de-energized. If the pressure is low, a failsafe kicks in to prevent the clutch from turning on. The failsafe kicks in if the pressure it too high, also. Your pressure is not high.