I know this topic has been talked about for years about these year model trucks but for what ever reason, mine is being a special kind of pain in the ***.

Here is what its doing. I switch the selector switch (manual) to floor, defrost, it works fine. panel, ac, max ac, all comes out defrost. Panel-floor comes out floor and defrost. Hot or cold, doesn't matter. The temp of the air is not the issue.

Ive read everywhere for weeks and all i keep seeing is VACUUM leak. OK, so i check the lines, check valve, canister everything seems to be ok. So i move to inside the truck, under the steering wheel, there is a small can looking thing with a arm on it (vacuum control motor panel/defrost door) i believe is the fancy term for it. I unplugged the red vac line from the bottom, and pushed it down, put my finger over the hole and released the arm. it stayed down, ok so that's good. with the truck running, and with it being selected to max ac the arms pulls down and stays there, pull the line off and got plenty of vac on the line. So i remove the control unit, pull the line connector off and i have vac there. So im thinking bad switch right? So i get a "new" switch try that. out the defrost still. And i haven't got the slightest clue as to why. I reckon what is throwing me off is I actually have vacuum all the way to the switch. Is it enough vac, i think it is. As much that can come out of that little black hose on the plug.

So with all that being said, does anybody know of ANY other lines, doors, switches, etc that can be checked, with or with out removing the dash. because im simply lost. Ive been working on this issue for weeks and i cant seem to find the problem and im extremely close to taking it some where and just having them fix it whatever the cost, because its extremely frustrating.

Any help would be greatly appreciated, and i will try to answer any questions yall might have to help diagnose.

01' S-Crew 5.4 4x4

 

The blend door are notorious for hanging up & or breaking on a hinge pin, thereby, not functioning correctly. Have you check all the fuses that control your HVAC?

You hit a point of is there enough vacuum?? Your gonna have to get a vacuum gauge on that little line and see what it reads. Maybe one of your parts stores has one to rent? Any place in the vacuum system that has a slight leak can present a issue with supply to the HVAC. SO if/when you get a vacuum gauge start with the engine bay and see what you get there...should be at 16-22 inches of vacuum and a steady needle. ( there are lots of Youtube videos that can describe different variations of readings)... then check on the inside.