It sounds like there is a problem with the mode door actuator. This actuator is what changes the airflow direction.
To get you started on the repair, take a look through this link. It covers in general how to repair this issue.
Now, this vehicle has a mode door actuator for the defroster door and one for the floor and vent. Here is what I would suggest. Remove the floor/vent actuator and see if it responds when you change airflow directions. Do the same with the defroster actuator if the other one doesn't work.
I attached directions for the removal and replacement of both in the attachments below. The defroster mode actuator is behind the glove box. The floor/vent actuator is on the left side of the instrument panel. Both are attached to the HVAC unit.
Let me know what you find or if you have other questions.
See pics below.
Images (Click to enlarge)
Wednesday, October 13th, 2021 AT 6:36 PM