If you have one room that is always too cold or too hot, check the damper to see if it is closed. You can use dampers to close off heat or air conditioning to one area of the house while forcing more airflow to another section that is used more often. When I was in Michigan, the “W” was set to the full open position and the “S” was set at a 45 degree angle which would cut the airflow by 50% in the summer. If you see and “O” that is for open and “C” is for closed. You may see a markings on the ducts that have a “W” for winter and and “S” for summer. In many areas of the country, homeowners will adjust the damper depending on the season. If the ducts are unmarked, now is a good time to mark the ducts with a Sharpie pen to indicate what room the supply duct goes to. The damper is closed when the handle points across or perpendicular to the length of the duct. When dampers are installed correctly, the damper is open when the arm of the damper handles points down the length of the duct. How Do I Know If A Damper Is Open Or Closed?

That is why they are often called zones dampers. The dampers can either allow or restrict airflow to different areas or zones of your home. Dampers can be rectangular or round and are designed to control airflow through your system. Maybe you are thinking what are those handles on my air duct for? Those handles are connected to dampers inside your duct work. If you are looking at your ventilation ducts, you may see small handles on the ducts.

Air conditioning vent adjustment