Ac Vent actuator not working

Hello, I have 2016 Peterbilt 579. My truck is suddenly just blowing air from the front vents. The windshield or floor vents are not blowing air at all. I believe the problem is with the vent actuator that controls the air flow, but I don’t know where it’s located on the truck. If anyone knows, plz help me. Pictures would be great.

 

I found then. There are two. One is right at front that one is ok. But can’t reach the one on the left side of the fan. That may be defective. Not sure which of them serves which perpose

 

I found the problem. Actuator is working but the air door pivot which is rotated by the actuator is stuck. Anyone knows how to free it ????

 

Do I have to replace it or can it be fixed. And how much would it cost to fix or to replace?

 

Thank you brother!