Found this booster fan, 6" diameter, inside the 10" pipe leading to the 2nd floor trunk. The booster was placed less than a foot from the A-coil on top of the furnace. Removed the booster fan and lo-n-behold, LOTS more air now gets up to the 2nd floor.
Q-Anyone ever have a booster fan that actually improved airflow? I have seen only a few and they have never been placed properly, they end up just getting noisy and annoying for the homeowner.