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Should You Leave Your Air Conditioner Vent Open or Closed?

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Does Closing Vents Actually Redirect Air to Save Energy?

Article updated: August 2025 

If you've ever wanted to lower your energy bills, you may have been told to close the air vents in unused rooms. While it seems logical to stop the air conditioning in empty spaces, this common practice is actually a popular HVAC myth. The truth is, closing vents wastes energy and can seriously damage your HVAC system!

The Risks of Closing Air Vents

Closing air vents in your home can create several problems for your heating and cooling system. The main issue is that it dramatically increases the static pressure inside your ductwork. An HVAC system is designed to have a specific airflow, and restricting it forces the system to work harder, leading to the following issues:

  • Ductwork Leaks: No duct system is perfectly sealed, and closing vents makes existing leaks worse. The high pressure forces conditioned air from your ducts into unconditioned spaces like attics, crawl spaces, or wall cavities. This means your air conditioner or furnace has to work harder to maintain a comfortable temperature, which, in turn, drives up your energy costs.
  • Wear and Tear on Your HVAC System: The increased pressure and reduced airflow can cause serious long-term damage to your HVAC system.
  • Blower Motor Strain: Whether you have a single-speed or variable-speed blower motor, it will have to work much harder to push air through the restricted ducts. This uses more energy and shortens the lifespan of the motor.
  • Frozen Evaporator Coil: When airflow is too low, the evaporator coil on your air conditioner can get too cold and freeze over with ice. This prevents your AC from cooling your home and will require a service call from a professional.
  • Heat Exchanger Damage: In the winter, low airflow can cause your furnace to overheat, potentially leading to a cracked heat exchanger, which is a dangerous and costly repair.
 

What About the Winter? Should You Close Vents to Redirect Heat?

The negative effects of closing vents apply to both your heating and cooling system. Closing vents in unused rooms during the winter to push heat to other parts of the house will create the same pressure issues, leading to increased wear and tear and higher utility bills. It's always better to keep all vents open.

 

How to Actually Save Energy and Improve Airflow

Now that you know the damaging effects of closing air vents, what are some effective ways to save energy and make your home more comfortable?

  • Check for Duct Leaks: Have a professional inspect your ductwork for leaks and seal them. This is one of the most effective ways to improve airflow and efficiency.

  • Consider a Zoning System: A zoning system uses multiple thermostats and automated dampers in your ductwork to precisely control which rooms receive conditioned air. This is a great way to save energy without harming your HVAC system.

  • Invest in a Smart Thermostat: A smart thermostat can learn your schedule and adjust temperatures to save you money without sacrificing comfort.

  • Schedule Regular Maintenance: Having a qualified technician perform regular HVAC maintenance ensures your system is running at peak energy efficiency and can catch minor issues before they become major repairs.

 

Need Help with Your HVAC System?

If your system needs repairs or you're considering upgrading to a new, more energy-efficient AC system, don't risk a DIY fix. Contact the local HVAC experts at Donley at (602) 698-8912 to make sure the job is done right! We serve the Phoenix, AZ area and can help you achieve a comfortable home while saving on energy bills.

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