Thanks to Big Jim M and JP02XLT, I used both your suggestions. My truck's problem was the air stopped blowing out the front vents on the dash. Floor and defroster would all work when I moved the switch, but when set to AC and Max AC, the cold air would only blow out the defroster vent in the dash on top the windshield.
I traced the hose going to the firewall back to the vacuum ball, and pulled the end off the vacuum ball and sucked on it, and there is a leak. Removed the wheel well cover on the passenger side to inspect the hoses where they go into the firewall, everything looks good. I then went up under the dash behind the glove box and disconnected the vacuum connector with the five hoses. I then took a piece of spare tubing and worked my way around the white connector, blowing and sucking on each line one at a time. If you listen carefully, you can hear each diverter or piston reacting to the vacuum.
Hooked it all back up, and my front vents now work. Don't know for how long, but its a start. I'm in Florida, so I will just leave the switch to Max AC for the next 5 months anyway. I still feel a leak when sucking on the firewall hose, but I don't see how to change out the hoses on the connector on the firewall.
If I have to get at the actual hoses behind the connectors, or replace the piston/actuators that move these diverter doors, my research has convinced me I have to remove the whole dashboard. Anyone else can confirm this?
Thanks again!