Recently bought a 2000 chevy express van with almost new motor (5,7 vortex), Dash vents stuck on defrost and foot vents, Did a little U tube and trace problem to Blend door vacuum lines, Harness under dash is good but end of grommet thru fire wall was feasted by rodents. lines are yellow, brown and black. Only found one black line that goes under vehicle to rear vent thru some kind of solenoid. I've been googling and U tubing and no diagrams that look remotely like mine. Dealership is no help cause vehicle is too old. Can anyone help me to where ask or get info w/o having to pay hi mechanics fees. Thanks in advance...

 

fine the main source vacuum line that goes to the engine intake