# Air vent switches to defrost by its self while driving.



## 05 GTO 88 (Oct 15, 2009)

A couple weeks ago I was driving with my AC on and all of a sudden the air stopped blowing out of the upper vents and started blowing out of the upper dash vent. It will keep switching between the two while driving. It does this almost every time I drive now. Why is this happing? I did recently install a Double Din HU. 
Thank You.


----------



## theGOATfather (May 5, 2013)

You're not alone in this. Mine does something similar to what you're saying. If I put mine on the defrost and feet combined setting. It will work fine for about a minute, And then like as if the door was closed the air will stop coming out. The blower is still on but there is no air coming out. It only does this on that one specific setting. I did some research and didn't come up with much. I too am curious what causes this.


----------



## 05 GTO 88 (Oct 15, 2009)

theGOATfather said:


> You're not alone in this. Mine does something similar to what you're saying. If I put mine on the defrost and feet combined setting. It will work fine for about a minute, And then like as if the door was closed the air will stop coming out. The blower is still on but there is no air coming out. It only does this on that one specific setting. I did some research and didn't come up with much. I too am curious what causes this.


Well, it seems like we are going to continue to wonder why this is happening to us. Haha


----------



## GTO JUDGE (May 14, 2005)

Sounds like a vacuum issue. In the "old" days switches worked via cables. 
Perhaps there is a vacuum leak?


----------



## aussie monoro (Jan 6, 2014)

on the firewall in engine compartment behind the engine there is a rubber vacume hose and it has a plastic non return valve, sometimes it gets carbon or crud in it and will cause the vents to move to defrost.
it is hard to get to.


----------

