First time I fired up the furnace on our Solera it seemed like very little air was coming out of one of the outlets. I took the grill off and found the house plugged with what looked like Fibreglass Insulation - how it got there I have no idea. You may want to pull grill off of the offending duct and make sure it isn't obstructed or perhaps not connected to the grill.
Ed (N4RWU) & Becky Taylor
Mistie (Walks 4-down)