Vacuume wipers and ac vents

[jeffjb]

My ac vents close when I go up a hill and open when I go down the hill and decelerate the vents open allowing cool air into the cab. It reminds me of my old Jeeps with vacuum wipers. When you go up a hill they slow down to almost a stop but when you decelerate the go like a bat out of hell.

[kizwiki]

The vents in your cabin are controlled by vacuum. you have a vacuum leak.