when accelerating the a/c stopsblowing out of the main vents and is diverted to the defrost vents. what is making the vents do this?
Possibly a Vacuum leak if your damper doors are controlled by vacuum.
http://www.ford-trucks.com/forums/1077168-a-c-blower-defaulting-to-the- defrosters.html -- check this out. It will explain how to fix this for you. Hope this helps
Absolutely a vacuum issue. dandyoun is right. When you accelerate the manifold vacuum drops to a point that the HVAC gets 'confused'
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