It is the door itself thats busted. Look up through the blower hole and you'll see exactly where it came from. You can replace just the door but you'll have to buy the entire box, actuator and door assemby ($26).
After you get the new part you can surgically remove it's door by cutting the box it's mounted in. Then, remove the glove box and unscrew the screws that hold in the actuator motor. Leave the blower motro out so you can get your hand up there. (look at the new part to see how it comes apart). Then simply install the new door into the old housing. Doing it this way you only have to remove the blower motor and the glove box, takes about two hours.
Or you can take the whole dash apart and replace the entire assembly with the one you purchased.
You may wunder how I know all this. I had a leaf in my duct and I stupidly reached up and pulled on the door through the blower motor opening. It broke rite off and well, you know the rest. . :{
Scotty