I have a 2001 blazer LT with the 4 button 4wd the problem I am having is my lights just flash when i go into 4wd i checked the accuator under the battery and I have no vacuum there or on any other lines I have been going through this forum and couldnt find and answer and also my HVAC is stuck in vent mode which I am assuming is also due to the vacuum problem i am having could anyone tell me how the vacuum lines should be ran I have tracked them all and wind up at the fender but have no clue where it goes from there

 

the one in the left fender is a reserve i believe. most likely you have a vac line up under the dash unhooked

 

Where does the vacuum to the reserve come from I see a line going into it but where does it go from there I can trace all the lines but i dont see any going to the engine

 

supply is on driver side upper intake.When you take off air intake you can see it.