How To Adjust A/C Duct Dampers

Posted by: Mas Broto
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How To Adjust A/C Duct Dampers

A central air conditioning system distributes the cooled air throughout your ductwork. How much air each room gets depends on the duct damper settings. These plates, which are located inside the ducts, are adjustable. A/C duct dampers can be opened or closed as much as needed to comfortably make the rooms they control.

Different rooms in your home need different amounts of cooled air. That’s why you need to adjust the air conditioning dampers to control and balance the airflow.

What is an HVAC damper?

It’s important to know what dampers are before you try to change them. These are plate-shaped devices that control how much air goes through vents and ducts in HVAC systems. Dampers push hot or cold air into different house parts when moving. This changes the temperature inside. Adjusting the dampers on your air conditioner is a simple way for homeowners to change how much air comes into each room.

If you know how your heating, ventilation, and air conditioning system works, you may know where the dampers are. They are usually put in places where duct systems branch off or split. The rod in a manual damper can be moved with a lever or a screwdriver.

Do I have dampers in my HVAC?

Not every house has a damper. If you have a modern HVAC system with zoned heating and cooling, the unit controls the dampers. But just because you don’t have a modern system doesn’t mean you don’t have one. You can’t know if you have dampers in your system unless you look at them. Go to your furnace and find the main ducts that leave the unit. If you have A/C duct dampers, they will be on those runs, just a few feet from the unit.

AC Damper Adjustment – Step-by-Step Instructions

  1. Open all the vents or registers in the house for the AC unit. Find the air conditioning duct trunks that go from the furnace to the outside of the house. Find the lever for each damper on each duct. On the side of each duct is a metal lever. Move the lever on each damper, so it points in the direction the duct goes, not across it, to open it. The air conditioning isn’t slowed down when all the balancing dampers are open. It’s working as well as it can.
  2. Close any balancing dampers that lead to rooms that are already cool enough with the AC. Turn the metal levers to face the opposite direction of the ducts across them. You might also want to close the dampers on ducts that go to small or unused rooms. They don’t need much cooling, but because the dampers don’t shut all the way, they will still get a small amount of cooled air.
  3. Wait a few days and keep track in your head of how hot or cold each room is. Find out which rooms are comfortable, which are too hot, and which are too cold.
  4. Go back to the air conditioning dampers in the furnace ducts. Adjust the air conditioner’s dampers, so each room gets the right air. Open the dampers on the ducts that lead to warm rooms. If a room is too cool, close the dampers a bit. Make small changes. Don’t fully open or close any dampers.
  5. Repeat step 4 after a few more days. You need to keep doing this until every room in your house is cool enough for you. When you’re done balancing the air conditioning dampers, use a permanent marker to draw a line on each furnace duct. Each line should go out from the handle to show where the position should be. Put an “S” next to each line to show that the setting is summer.

Since cold air doesn’t rise, you need to force air-conditioned air into the upstairs rooms to cool them. When you switch from air conditioning to heating, you need to adjust the balance of the dampers again.

Adjusting your duct dampers takes time and patience, but it’s worth it in the long run if you want to get the most out of your unit and keep your home comfortable all year. If adjusting your AC dampers doesn’t fix the problem with your heating and cooling, call a professional for help.

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Mas Broto

Have been in the heating and air conditioning (HVAC) industry for over 20 years. He is person that will grow and thrive to learn more about the HVAC industry throughout his career. Mas Broto is also a blogger, who's dedicated to bringing you the best knowledge to get ahead in the game of life.

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