Window AC vent open or closed?

Window Air Conditioner Vent Open Or Closed?

Have you ever wondered what the vents are for on window air conditioners? If so, you’re in the right place.

If the vent on your window air conditioner is closed, the unit is recycling the air that’s already inside the building–if it is open, it allows air from the outside to come in.

Now that you know that the vent is used to regulate the source of air that your window air conditioner is using. Both settings have their purpose which I am going to describe in detail below.


When the air vent on your window ac is open it is allowing the outdoor air to come in through the back of the unit and into whatever space it’s supposed to be cooling. This may have an effect on the set temperature of your unit.

The drawback to keeping it open is if the air outside is hotter than the desired indoor temperature, then your window unit may be overworking itself to keep the place cool. This is why it is important to close the vent when you’re trying to reach a desired cool temperature.

What opening the vent allows you to do is cycle fresh air into the room. This can be especially handy for vacation homes or spaces that aren’t frequently inhabited as long term vacancies can cause the air inside to go stagnant.


When the vent on your window air conditioner unit is closed it simply recycles and cools the air that is already inside the building.

A closed vent can save on energy and cut the cost of keeping a space cooled down by keeping out warmer outside air. The vent on your air conditioner should always be closed if the objective is to get the place to a cooler temperature.

Opening and Closing the Vent

The control is going to differ between all the makes and models but you can expect the control to be in one of these three forms. You can tell if the vent is open or not by looking through the unit–if you can see outside then the vent is open, if not, the vent is closed.

  • Control Button.
  • This control is in the form of a button on the remote control, or on the face of the window unit.
  • Sliding Lever
  • The sliding lever can usually be found on the front of the window unit and it is used to manually open or close the vent.
  • Damper knob
  • This is a manual method like the sliding lever and can usually be found in the same spot on the air unit. The only difference is that the damper knob is pushed in and out, and not slid side to side.


Whether the vent on your window unit should be open or closed really all depends on you and your needs.

If you want to cycle in fresh air from the outside you should open the vent on your unit until you feel the place has plenty of fresh air inside. You can then close the vent and resume cooling.

If your main objective is to keep the cool air, you want to leave the vent closed and just recycle the air that is already inside.

If you have any further questions you should reference the owner’s manual specific to your make and model.