Not sure how to list this and the searches I ran didn't seem to help. So here goes.

Anytime I accelerate, either from a stop or going in to passing gear, the air from my A/C system stops blowing out of the dash vents and is redirected to the defroster vents. I'm sure this is a vacuum line issue, how ever I don't know which to look for and I'd like to avoid replacing every line in the truck at this time. I don't hear the damper close hard or anything like that.

Has anyone else had this issue or know where to begin?

Thank you

 

Search "wild vents".

This is a common issue and has been discussed hundreds of times.