Except there is a low pressure switch that will keep the clutch from engaging if there is insufficient pressure in the system........

I did run another can of refrigerant into the system today and the clutch never moved. However it was cold out today, my OBC was reading out in the low 50° at the time I put the extra refrigerant in, could that have kept the clutch from engaging? I didn't hit the defrost button as I didn't want the flap to move to recirculate and get stuck in that position again.