My wife drives a 1997 740I she got init the other day and the ac did not work. I checked it out and the heat does not work either. The unit lights up all the displays are corecct when you press the button to switch from say your feet to defrost you hear it switch as if it did the switch but no air comes out from any where on the car nothing. I check the fuse under the hood and it appears fine. Its hot and so is she anyone help me