Hi Guys ,New guy here with a question.My Air conditioning stop blowing out the dash vents when I am accelerating it goes to the defrost vents and when I let off it will blow out the dash vents again.The air system work great its very cold.Just wont blow out the dash vent when the truck is accelerating.Need some help with this one Thanks AZLawson

 

Look for a vacuum leak somewhere. There is a vacuum cannister under the hood somewhere. Also check the vacuum lines going inside the truck for any leaks.