Blend door? Recirculate a/c inside air vacuum?

J-Dub said
Factory air all rebuilt and blower works and a/c works and newly tested. but seems to be drawing arizona outside air (it doesn't keep getting cooler as you drive) I suspect i can prop open the blend door (or close it?)
**This may help troubleshot: I do seem to have a vaccuum issue in that my blower won't stay blowing through my vents unless I pinch off a vacuum line that goes to a round rubbervalve thing on upper left, which moves a lever). lines and the rubber thing are solid and newer looking.
ANY IDEAS or where can I find the blend door? Thanks!!!

I do not know specifically about your car but many older cars with vacuum operated servos would default to defrost mode if there was a insufficient amount of vacuum or a vacuum leak. I would disconnect the vacuum line in the engine compartment that supplies vacuum to the heat-a/c control. Disconnect it from the engine and connect a vacuum pump and see if it will hold vacuum. If not, pinch off vacuum lines under the dash one at a time until you find the leak. Easier to start there before tearing things apart.