since I purchase my home in 2004 one of my bedroom air vent is clogged. Air flow is very low and no heat come out of it. I try to stick a vacuum in the duct but no luck. I ever try to stick a mini video camera to see but after going 16’ the duct took a hard turn and could not see any further. I try to call HVAC people but they are puzzle too. It seem like clogged air duct from upstair take a dive in between kitchen wall then under garage to furnace. Help? Should I take furnace duct off next? Is it easy to do?