good evening. 1984 300D here, california edition.

what are the "default" settings of the vent flaps when vacuum is removed? my main vent flap is closing while my car is on, and in lieu of a legit fix i'm interested in capping off the vacuum before it reaches the climate control center if that will keep my vents open and allow air into the cabin. what is the vacuum layout like once through the firewall? i have yet to delve into dashboard mechanics. i'm aware that one of the "other vacuum consumers" is the ignition shut off. what can i expect? can i get to what i need through the kick panel?

here's the problem

its cold now in my part of the world. i have a climate control issue that i've not cured and am thinking of a quick fix. you see, my main vent flap closes when my car is running, or better yet when there is enough vacuum built up to keep it closed. say i get into the car after it has been off for several minutes, turn the key over to wait for the glow plugs to warm up, and the blower is on - air comes through the vents then. i start the car, main vent flap closes - yes all actual vents stop emitting air, except that actually a little trickle comes out because the main vent flap seal isn't perfect. fan blows full steam, air gets hot, it just doesn't come out.

this started last winter. i noticed then, as now, that i could get air to come out of the vents with the car running by turning on the AC and switching the temperature to cold. this is the only setting that is apparently allowed by the main vent flap, and i suspect the acc unit is deranged and the real culprit. last year i hit a deer and that solved the problem until it warmed up and i got the car back on the road.

and now its cold again.

thank you for any insights you may offer.

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1984 300D "Brown (and Blue) Betty" Over 200k but the odometer isn't counting