A/C vents not blowing out?

MY 85 GT

10 Year Member
Mar 7, 2008
1,852
208
104
New Jersey
A/C vents not blowing out only comes out the defrosters in any postion i put it in...My oil gauge is all funky now this all because i cleaned my STUPID engine compartment...How do i get the vents to blow out again????????? what controls them.
 
there is a small pastic vacuum line that comes out of the firewall just above where you heater hoses go in the firewall. that is what controls the vents in the dash. should be a small pastic three way valve there then is goes to the main vacuum on the firewall and to vacuum ball in fender check the line for for cracks.