I've done a bit of research and still can't find a solution. Our AC system blows fairly strong and cold downstairs but barely blows at all upstairs. The house is a little over 3 years old, and approx. 1350 sq. feet. There is an Aprilaire zone control system in the attic wired to the 2 thermostats (I'm assuming) and the air handler and a wire running to a duct coming from the air handler that runs to a large box with several runs of ducting coming out of it. My guess is there are dampers in the ducting that should be controlled by the zone control system, but nothing I've done seems to change anything. I've reset the zone system and also tried turning off the downstairs thermostat to no avail. The AC unit is on almost continuously, but still blows very little out of the upstairs vents. I'm fairly handy, but don't know much about HVAC units. I also don't want to call someone and have to spend the $$. Help, it's flippin hot!