Vacuum Problems

[ford73power]

So I'm trying to solve a vacuum leak problem I've had since I got the truck a couple months ago.

When I bought it, the ESOF did not work, but the HVAC could select any vent hot or cold and worked.
In my attempt to fix the ESOF, I replaced all the lower vaccum lines (that go to the hubs) and still had a vaccum leak. I figured it was the hub orings and put off working on it until it got warm.
However, a couple weeks ago, I lost the ability to control my HVAC. Anything I put it on defaults to defrost with the exception of FLOOR ONLY which works as intented I believe. So to try and troubleshoot this, I first checked the vacuum pump. The resistance on the plug was not quite to spec, but when hooked up to nothing else (completely plugged from HVAC and ESOF), it held vacuum and ran with the key to ON. So i got out the mighty vac and noticed that when I pull vacuum directly to the HVAC line (the one that goes thru the firewall i think) it doesnt hold vaccum. Where does this line go and is it replaceable? Is it supposed to seal up and hold perfect vaccum? Im guessing I'll have to tear the glovebox out and try and find it. Any suggestions, experience, drawings that will make this less difficult? I havent heard of anyone having a leak anywhere but the hub lines, what gives? Thanks!!!

[STANGMAN893]

I have personally seen the metal lines that come out of the knuckle go bad and also the solenoid behind the pump go bad.Look into those.