Here is how to replace the dash vent (defroster) actuators. When they fail, the vents don't close so that the air conditioning blows up through the defrost vents rather than out the proper front ones.

1.) Get replacement diaphragms for dual diaphragm vacuum servos

2.) Remove glove box liner

3.) Carefully remove vacuum lines from actuators (plastic can be brittle!)

4.) Pry "whiz nuts" off mounting pins of vacuum actuators. Remove actuators, taking note of how they are installed. Digital camera works good for this sort of thing.

5.) Following instructions replace diaphragms in both actuators. Check both with MityVac when done.

6.) Install actuators. Connect vacuum lines and press whiz nuts back in place.

7.) Fire up ACC and check operation before reinstalling glove box liner.

8.) Enjoy AC out of dash vents.

Dan Penoff