climate control acting strange

[El Duque]

I've only had my Explorer for about a month now, and I've noticed something strange. I usually drive with the button pressed to blow through the dash vents and floor at the same time. But sometimes while driving, the air will suddenly switch to the defroster vents at the top of the dash, without me touching anything. Has anyone seen something like this? I did a search but didn't find much. Thanks

 

[waskly]

are you going up a hill when i does this?

 

[El Duque]

you know what? You just made me realize, I have been going up hills when this happens. Would that be something with vacuum? thanks

 

[El Duque]

bump

 

[waskly]

you are correct, over a long up hill, the vehicle does not produce enough vacuum and the vacuum reservoir runs out of vacuum defaulting the system.

only reason why i asked if its only uphills.

 

[sljkansas]

My Daughter told me the other day that our 03 Sport Trak, that the AC bounces from defrost to floor. I had a feeling it may be a vacuum problem, I'll ask here if it only does it up hill or under her heavy foot. Any hints on where to start first.