94 AC/Defrost vent issue

Dear Forum Dwellers:

I have a nice old '94 'stang, it's just a 6 cyl, and will never see the track but it runs fine and it's a mustang. Also, despite 125K miles, it is still getting about 29 mpg if the wind is blowing right.

I have been having trouble with the A/C vent/blower. The AC blows cold, the fan works, but even with the switch in the AC position, the air blows out of the defroster vents and also the floor vents, and not out of the dashboard vents, where it is supposed to cool down my face. Even on "vent" the air blows out of the defroster.

Although it is not all bad having cold air blow on my crotch and also the top of my head, I would rather have it work right.

There is obviously some kind of flapper valve that directs the air either out the vents or up the defroster, and this thing is stuck.

Questions:
a. Where is it? How much of a pain in the neck is it to get to?
b. Does it run by electrical or by vacuum, or by cable or somethng, like the old ones used to.
c. Will it work to plug up all but one of the vents, and then blow compressed air down there backwards to free it up?
d. Other suggestions?

Thanks for all of your help.

Sure enough, I went out and looked at it, and the small vacuum hose that connects to the spigot marked "ac" is broken. Looks like a piece of cake to swap it out. I think about a two foot connector tube will do it.

I am sure glad I asked the question, because it probably would have taken me a day or two worth of profanity and knuckle skinning to figure this one out on my own.

Where's the best place to get another one? Ford garage? Auto store?