My vents will not change on my work van (2003 express 2500). There are a brown and black vacuum hose that is the issue. A service shop wanted to change out my 'bad control' after replacing the intake gasket, at $203 for the part I didn't let them.

Does anyone know if it is the brown or the black that is suppose to have the vacuum?

The black has the vacuum under the dash at the quick connect. From the switch to the connector I have no vacuum on the black. I can blown through the brown but not the black. Where I got confused is why it started working when I reversed the line at the quick connect to put the vacuum on the brown.

Any thoughts? Thanks!

 

I have a 2002 express 1500 that had the same problem. Check vacuum lines in engine compartment behind fan housing on fire wall. they are hard to get to but on my van the brown one was rubbing on something and made a hole. cut plastic line and slipped new rubber vacuum line over plastic one. also the vacuum line branches off and goes to top of intake main vacuum fitting my lines were also dry rotted with leaks replaced. Ac works how its suppose to and van ran better also. I found my leak with engine running and moving the lines underneath the ac housing i could hear the leak leak changing pitch.(be careful of fan). PS the brown and black lines you are playing with r suppose 2 have vacuum just look for them in the engine compartment side hard to see easier to feel .