Little black box...A/C

[crazeetxn]

I haven't got the first clue what the technical name is, but I'll describe it the best I can. On my 86, the air comes out of the vents and the floor. I took a cover (behind and to the left of the glove box) off the little black box that lets the air in and noticed the door will not open or close. It's just sits there in the middle position. When I take the plastic piece off the door, the arm will move when I change positions of the a/c switches. I've begun to notice it sounds like a vacuum leak at the switch and also down where the door is. I took the switch apart yesterday and ordered another piece. I've got a vacuum line coming off the carb that's pulling about 20 to a line that goes through the firewall up to the A/C switch.

Now...
1. What the heck is the black box called?
2. I reckon I'm going to have to take it off to see if there an actuator or something back there? If so, is the actuator replaceable or will I have to replace the whole little black box?

I appreciate all the help...

TNT

[$ilverado8405]

The black box is the blend door unit. There is an actuator that controls the door movement and it is replaceable.

[crazeetxn]

Now that I've got the tech term down, how do you remove the sucker to get to the actuator?

[Punx Life]

Perhaps this will help...

http://fullsizechevy.com/forums/showpost.php?p=3468132&postcount=10