Cannot selection to defrost or floor?

For that it is likely the clip that holds the cable in place on the side of the HVAC case. They fail and the cable gets loose and cannot move the mode cam. To get to it you remove the center dash trim using a couple of trim sticks to get it free from the clips. The HVAC controls come with it and you will see where the mode cable runs between the control and the mode door cam. There are repair kits if the clip has failed. Now if you can turn the dial and things move but bind up, use an endoscope camera to look into the HVAC case to see if something fell into the case and is blocking the doors.