My 2004 bmw 325xi has heat on all the time which overrides the AC I can feel the ac in the side vent on. I removed the HCV and found no continuity over the solenoid. No Resistance read. The plunger was free to move. The power supply when tested with the car turned off had 12 v when the car is turned on key in ignition 12v when AC on and car on 12V at the plug. I ordered a cheap HCV to install as a test but am wondering if the HVAC controller is compromised. How do I test that unit. I can get it out of the car. I don't have one to swap in. I have not used the car much and no indication that the battery is draining which does not make sense as I have a constant 12 v to the HCV