What does a vent actuator do? Is it right next to the blower motor? Reason why I'm asking is because I was having issues with both the heater/AC as far as air flow goes. Mostly the center vents. It always sounded like a flap would shift prior to loosing air regardless of fan speed. I did change out both the blower motor/controller and still the problem is there. I also saw this gray looking box next to the blower motor which I think is the vent actuator. Can this be the problem? Where is it located?

Thanks