the accuator, located in the rear passenger side is bad. the controls in front when turned go to an accuator in the rear there are two of them one for hot/cold and one for the vents.
In 2003-2006 Chevy Tahoe, suburban and full-size trucks with Bose, the factory subwoofer is in the center console the console houses the enclosure and the sub fires forward under the dash.