I bought a replacement inner a/c heater box for my '72 with a/c. The flapper defroster door at the top is not closed all the way as it sits out of the car. When I suck on the actuator valve connected to it it opens up all the way. Is this door supposed to remain about a third of the way open? I would like to make sure this thing is adjusted properly before I install it, but I don't know how it is supposed to operate. Oh yeah, when I pressurize the valve or blow into it the door seems like it is trying to close up all the way.
Thanks Chris