I bought a 2000 chevy express van. Almost new engine but ac vents are stuck on defrost and feet vent. traced it to vacuum hose under dash and its all good till it goes thru firewall. Yellow,browm and black vacuum lines thru grommet inside engine bay behind battery tray where feasted by rodents. Can not find other end were they connect except for black line that goes under vehicle to a solenoid that I think goes to rear air. Dealership says it to old of system for digital diagrams. Blend door harness its no longer made but im sure I can fix that, just need to know where they connect. Any ideas out there. Been googling and looking for old diagrams but no luck yet...

 

This is for a 1999 but its as close as I could find:

 

Thank. you. ill. compare with the other prints I have. I also decided to go to salvage yards and try to find similar vans to get better visual.