Recently I have been having issue's with not getting air through the pannel vents (Face vents). The air will just blow through the defrost and the feet vents. I do notice that when I have the truck in the accessory position I can some time get air through the panel vents but when I start the truck it goes back to the feet and defrost position. not sure if it would be a stuck actuator or a bad one or where and which one would cause the issue. It's 2005 trailblazer v6