A/C switches to defrost.

[koda2000]

I have a problem with my a/c controls which seems to be related to low engine vac. if i have the a/c on and blowing from the dash vents and climb a steep hill the a/c will start blowing out of the defrost vents. as soon as i'm over the hill the a/c will switches back to the dash vents. the control switch is electric but there must be a vac switch somewhere... where?

 

[jab2007]

Try and check the blend doors if they are moved be an electric motor it can be that mabye the blend door or the motor it self can be culprit, however also check all the vaccum line and check for cracks that can also cause a problem. Good luck.

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the A/C & heater section. Check the color coded hard plastic vacuum lines where they meet the rubber connectors for cracks.