I just purchased a 1971 Hearse with the 472 motor. The a/c works great but only blows out of the center floor area. The control will not change where the air comes from. Any Ideas or direction in which to go to check this would be greatly appreciated. Thanks Ben
The blend doors are vacuum controlled - check all the vacuum lines under the dash - for starters. There's a bunch of them between the control head and the programmer (heater box).
Also check to make sure the vacuum source from under the hood is connected.
Sometimes the ports on the head or programmer get clogged-up, especially on a car that sits/has sat for a long time.
It could also be debris in the heater box (leaves, mouse nest, etc.) that prevents the blend door from moving.