Solomon from Advance Auto Parts said:
This Dorman Air Door Actuator - Part # 604-400 is behind the driver knee air bag. The air inlet actuator - part # 604-251 would be located behind the glove box."
Rocky, I don't know if the passenger side actuator is much different from the 2011 Fiestas, but if it is, it's a lot easier than the one below the steering column. The part looks the same, but the passenger side only has 2 prongs in the connector instead of 5 (I think).
You first remove the glove box by opening it and pressing both sides in, letting it drop down (remove everything first). You'll then see the actuator on the left side, and it has the same 3 Torx screws. Attached is a picture of the ST after getting the glove box, the actuator is the is next to the fuses.
As an added note (don't know if it has been mentioned before): The steering column actuator (5 connectors) will work on the passenger side if you open it and rotate the gear so that the notch aligns and fits correctly. The passenger side will NOT fit the driver's side actuator (learned this the hard way at the same time that I learned that there are 2 actuators, after 4 times of replacing the same one, it gets easier ha!).