I have a 2007 silverado new body style and my air only comes out the top vent have tried replacing both the servo and controller. I can get the vent to work manually by moving it by hand. I checked it have good power and ground going to servo and it goes through a starting sequence but just goes strait the top vent after. Is anyone else having this problem?

 

there will be body codes to help diagnosis. Record all the dtc, clear them and post what returns.