ok sorry but I let the car get to operating temp and the compressor is kicking on. I checked the pressure and it was fluctuating between 28- 32 or so. Does the car have to be running and the ac on, to properly check the charge level? I am just trying to verify that the compressor is definitely bad before I spend the money for a new one. I blows air, just not cold. The compressor does not make any abnormal noises.