Go in through the 2 main dash panels and follow the y ducting for defrost down to a big chamber. There is a drum inside that rotates to direct air. Actuator is on the left of it. Pull the actuator and grip the drum stub with you fingers and see if it moves. If it moves you need an actuator, if it doesnt there is some spitz or a pen caught in the drum. You can try blowing air down the defrost as you wiggle the drum to dislodge it.
I took out the y ducting and opened up the drum you are talking about, air flow is weak coming out the defrost vent and the knob to change to floor or defrost makes a clicking sound even though i changed out the actuator to rotate the drum