Ford 7.3L Power Stroke (1999-2003) :: A/C Won't Blow Through Front Vents?

After some diag I got the A/C to blow out the front vents. There are million threads on this issue half of them are never figured out. This is the second time I have come across this problem so will make this really informative for those who have this problem. If you A/C blows to defrost, yes most of the time its going to be a vacuum leak issue.

Step 1) turnkey on engine off, stand by passenger fender and listen.. can you hear the pump running? If it is your pump isn’t dead.

Step 2) does the pump run for 30 seconds then shut off? You may not have a vacuum leak. If keep’s running for ever you have a leak. Inspect all lines, especially those going down to the hubs for cracks. Also inspect vacuum lines under passenger glovebox.

Step 3) can’t find a leak? Disconnect the line going to the ESOF solenoid and plug it, if you pump stops running then your ESOF solenoid has an internal leak. That was my problem 6 months ago, replaced ESOF, A/C blows normally.

Try This Second! So my AC isn't blowing through my front vents again.... (more diag)

AC not blowing through vents and can’t find a vacuum leak? Take off glove box door, turn AC control switch to floor/defrost/front vents, watch the metal arm connected to the side of the big black box move up and down into various positions. I noticed on mine the arm will go down in positions (floor or defrost) But it will not move up! Which needs to happen to switch to front vents. If I push the rod up by hand manually, the ac will blow through front vents, and stay blowing through front vents even after I let go. PIC of metal arm thing connected to diaphragm, which changes air flow by moving flap inside the big black box

I am guessing the Diaphragm is the issue? The truck will continue to blow from the front vents even when the truck is shut off and restarted, it will stop when I switch the ac to a different position, it will not return back to front vents.