Go to one of your local parts houses and purchase a Haynes Manual that is specific to you truck. It will have the vacuum routing as well a wiring schematic.
There are two vacuum lines on the ignition switch (where you put the key in). Remove the coverings to expose them. Check to see if the lines are loose, clogged, or disconnected.
The vacuum that operates the doors for an ac system is created from the vehicles engine. Check under the hood for vacuum lines that have cracked or have become disconnected to start.
its a diesel, it doesn't have vacuum lines.
The automatic hubs are activated by vacuum. Check for broken or disconnected vacuum lines especially behind each front wheel.
there is a good chance the main vacuum supply line from the engine that feeds the HVAC system is broken or disconnected. Inspect the vacuum lines under the hood.
The vacuum supply line from the engine is probably disconnected or damaged. Inspect the vacuum lines under the hood for damage.
"System lean, bank 1" First, I would suspect a vacuum leak. The engine is getting unmetered air. Check for disconnected vacuum lines, cracked rubber/plastic vacuum lines on the engine, on the firewall, in the engine compartment.
Check the vacuum lines on the driver side of the engine.
Sounds like you lost the vacuum supply to the controls. Check under the hood near the master cylinder area for cracked or disconnected vacuum lines.
Good chance you have a vacuum leak somewhere. Check all your vacuum lines under the hood, look for one disconnected or cracked.
Vacuum lines supply vacuum for various functions.
The HVAC controls operate off of vacuum supplied from the engine. If the vacuum supply is cut off the system defaults to the defrost mode. My guess is the vacuum supply hose is disconnected/broken/cracked or pinched, start by checking under the hood and inspecting the vacuum lines.