I'm the proud owner of a 2 story georgian outside of Chicago, so we get our fair share of hot/cold weather . Furnace in basement, and it sends ductwork to basement, first level, and 2nd level. Basement is about 75% finished, and drywall there covers a lot of ceiling, where ductwork may hide. I have two rooms on 2nd level that have very poor airflow thru their registers for both heat and cool, while other rooms on 2nd level have good to excellent airflow. I speculate it is a damper issue - the damper in the ducts that run to these rooms are closed. Problem - how do I find the ducts/dampers that run to these registers? all registers are on the floor/wall intersection, so the ducts likely run inside the walls. I can find some dampers, but not the ones for these rooms, in the crawlspace near the furnace. Is there a method to work from the register backwards to the furnace to find the correct duct? Many thanks.