There are two movable baffles ('doors') in the typical heater. One is the
blend door which moderates the heat temp.
The other(s) gates the outlets...they are usually vacuum operated, by a
diaphragm actuator mounted on the plenum assembly
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
Take out the plastic insert from the top if the instrument panel. I don't
the hose color, but conversion companies often tap into the vacuum system via
the vacuum lines under the cover. It's not unusual for the tee fitting they use
(Conversion Vans: the #3 reason I hated working on cars for a living. Yeech.)
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