Hey Chris. Your A/C ducts in your dash are controlled by little doors that direct the air flow. On modern cars the actuators that control the doors are electric motors. Older cars are vacuum controlled, but I believe yours are controlled with cables. You’ll need to take apart your dashboard and inspect the cable and the blend door itself. It sounds like your cable is binding up. If you can get in there and get some pictures, post them here and I can guide you further.