HVAC vents not working properly

When adjusting the force from my HVAC blower motor, sometimes I can hear a lot of moving air inside the dash but very little air comes through the vents. It seems as if all of the vents inside are partially open. Sometimes it blows perfectly fine through the vents and I don't hear the moving air inside the dash itself. All the Googling I've done, I have found things about the blend door actuator, but nothing about the doors/mechanisms related to the airflow/vent direction components. If I understand correctly, the blend door actuator effects how much warm and cold air get blended. That does not seem to be my problem. I can adjust the temperature just fine. When I switch vent positions, there is a delay, and often I lose vent pressure and hear the moving air in the dash. Any help or advice would be greatly appreciated!