BMW Repair: 2000 328ci troubles, thumb wheel, fuse box

Question
My AC will only blow cold air out of the dash vents, but if I turn off the floor vents and defrost vents, the air becomes warm. This means that as long as I maintain two sets of vents on (defrost + dash or floor + dash), the dash air will remain cold. However, this also means that I have to deal with hot air being blown into the car at the same time.

Shortly after finding this problem, I lost power completely to my AC unit. Nothing turns on or off anymore. The lights behind the AC controls still light up with I turn the car's lights on and off, but no lights light up if I try to select an AC function. I found the fuse box, but cannot find a fuse diagram so that I might check the fuses for the AC unit.

Thanks for any help you might be able to lend me on this subject...

Best,

-Bobby Whitt

Answer
Bobby, the fuse diagram in a white piece of paper on the back side of the fuse door in the glove box or between the two rows of fuses, The A/C control unit controls the blend and distribution doors for the heater/evaporator box. It also controls power to the heater valves to permit or dis allow hot coolant from entering the heater core. I also signals the Final stage resistor to vary blower fan speed. Make sure you are using the thumb wheel between the center vents. Since you are having problems with temp. and control function I would look toward the Control unit. Make sure the heater valve is working properly by measuring the three hose temps with and without heater operation. The control module is easily replaced but needs to be coded to the car by dealer style coding equipment to work properly. Check powers and grounds at control unit.
-Evan