Ac control panel runs with key turned off on 1998 BMW 328i

hi my control panel for my ac went out. i bought one from a used parts dealer, it works but when the car is turned off the unit is still drawing power it seems as if something is still running in the unit. any ieas??? i feel vibration and hear a buzzing noise

Asked by for the 1998 BMW 328i
Did you find out why the new panel was having problems? Was it the correct part?