Floor and winshield vents blow hot and cold air, but no air movement from dash on 2007 Chevrolet Silverado 2500 HD

you can feel both hot and cold air, but does not blow out of vents no matter what speed is chosen

3 answers
check your blend door actuator
blend door actuator or controller
This vehicle has the ability to store codes in the hvac control module as long as someone is using a Factory scan tool.
There are 3 doors / actuators: blend door ( temp), mode door ( defrost, floor, vent) and recirc door (outside air vs. Inside air)
Sounds like a problem with the mode door. Should be verified with a scan tool ( Tech 2)