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How to Adjust Dampers for Air Conditioning: 8 Reliable Steps

Winter is almost over. You have to adjust the damper at any cost before the heat starts taking over. Because nobody wants to spend the hot summer days without A/C. 

How to adjust dampers for air conditioning?

If you want to adjust dampers, first, turn the switch on. Then open the vents fully, locate the damper and levers, open them. Next label the opened ones. Keep some closed if no work is needed. Monitor and adjust while checking temperatures. These will help you get the A/C to the right temperature.

Now, do you want to give it a try? Let’s find out more on how to adjust these.

Adjust A/C Dampers: 8 Easy Steps!

Adjusting A/C dampers needs time and attention. But in order to do it yourself, you would need precision too. So, try following the steps in order so that you can adjust the dampers.

Step 1: Turn On the Switch of the Fan

If there is no other way to switch on the fan, try adjusting the thermostat. But sometimes there are mechanical switches. Then at first, turn that switch on for good measures such as plugging electrical outlets

Step 2: Open the Vents Fully

Make sure to open all of the air conditioning vents in the house completely. Even the registers in the house need to be open too. 

 Keep the fan with vents in the on position. If this isn’t the case,  then adjust the thermostat. This is to keep the system functioning while you work on the dampers.

Step 3: Locate the Damper Levers

Locate the duct trunks that lead from the furnace to the air conditioning system. On each duct, look for the damper lever. Each metal lever is found on the duct’s side. 

Dampers aren’t standard on all systems, for example using electric heaters. So try looking for them within a few feet of the furnace. This will help to determine whether you have dampers situated.

Step 4: Open the Dampers

Move each damper’s lever in the direction of the duct’s movement. However, do not put it across, to open it. 

The air conditioning airflow is not impeded with all of the balancing dampers open. It’s at its maximum capacity.

Step 5: Close Certain Dampers

To reroute air to other rooms, close any balance dampers that lead to rooms. These rooms are to be appropriately cooled by the air conditioning. 

You can find out where the ducts from the furnace travel by following them. This can save money on air conditioning. This also allows the system to cool more efficiently.

Then turn the metal levers in a perpendicular position facing the ducts. It’s also a good idea to close the dampers on ducts. 

This happens mainly when the ducts are small and unused. If it’s small you can try some alternatives of duct board.

They don’t require much cooling and aren’t entirely closed. They will still receive a tiny amount of chilled air.

Step 6: Label Damper Positions

Mark the position of the dampers located inside the duct. You do it when your system is balanced to your maximum comfort level. 

Step 7: Monitor Dampers and Make Adjustments

It’s time to adjust your dampers. Now that you are accustomed to which duct serves which rooms. Keep in mind that the damper lever is totally open. Especially when it is facing in the same direction as the duct:

  • Try adjusting your dampers to maximize heat. Do this as we approach the cold-weather season. 
  • Place the lever at a perpendicular angle for more airflow.
  • Turn your system back to auto. This has to be done after you’ve made your initial tweaks. Now, all you need to do is let it do its job.
  • Allow your system to operate for a few days. The process is done before assessing the level of comfort in each area. If required, re-adjust the dampers, wait a few days, and evaluate your progress. 
  • Rinse and repeat until each room is at ease. It’s worth mentioning, just make some modifications. When some people get home to a cooler house in the winter, they turn up the thermostat. They try to set it to 87 degrees in the hopes of speeding up the process. Don’t be the guy who does it. 
  • Also, don’t close all of your dampers entirely or you’ll be unsatisfied with the results. Little tweaks will save you time and frustration in the long run.

Step 8: Check the Temperature and Adjust Accordingly

Wait a few days and keep track of the temps in each room of your home. To acquire an accurate temperature reading, use an indoor thermometer

In order to buy these, you can take a look at these recommended thermometers. These work perfectly well indoors:

Product 1
Product 2

So that you can move around to different rooms. Check to see which rooms are the most pleasant, as well as which are too hot or cold.

Try to take it back to the furnace ducts’ air conditioning dampers. Try to adjust each air conditioning damper. Do this so that each room receives the proper amount of air. Close the dampers in ducts that go to overheated rooms. 

If a room is excessively cold, close the dampers a little. Make tiny changes; don’t entirely open or close any damper.

Finish balancing the air conditioning dampers. Next, draw a line on each furnace duct with a permanent marker. 

Extend each line out from the handles to determine the correct location. Make an “S” beside each line to show that the scene is in summer mode.

Repeat the damper adjustments after a few more days. Continue doing so until all of the components of your ventilation system are working together. 

This is to ensure that every room in your home is to your desired temperature. So that the dampers work well when you operate the thermostat.


Question: How to know if dampers are open or closed?

Answer: A lever on the outside of your duct turns the air control plate into a manual damper. The damper plate opens if the handle is in a horizontal position. The damper and passage are closed when positioned vertically.

Question: What is the key to increasing airflow in air ducts?

Answer: Cleaning the air filters and the ductwork can help increase airflow in the ducting. Weak airflow in places can be greatly improved. By installing inline duct booster blowers and/or air dampers, it is accomplished.

Question: Is it better to close vents in rooms that aren’t in use?

Answer: Closing the vents won’t help. Closed registers, however, help the air conditioner in cooling more efficiently. Force the same quantity to air ducts increasing system pressure. This makes it hard to circulate air.


I hope you now know how to adjust dampers for air conditioning. In the future, these will help you when you need to fix dampers.

So with that said, I wish that these damps are working properly. 

Best of luck!