Here is how I modified the styrofoam “ducts” to force more air out of the vents into the living space...
First shot is looking into one of the styrofoam “ducts”, facing forward toward the cab. I hand cut pieces of closed cell foam to fill up as much of the space as I could, and then wedged a final u-shaped piece just inside the opening of the vent to direct air back through the vent...
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