Does a Window AC Bring in Outside Air?

The answer to this question is essentially no. Window ACs don’t bring in outside air. They cool the air inside your home by pulling air from it, filtering it, removing indoor heat and humidity, and blowing it back into the house.

Window AC Unit

Does a Window AC Unit Bring In Fresh Air?

Air conditioners cool your home by reducing indoor heat and humidity. But they do not bring in fresh outside air. Air conditioners attempt to remove the heat from the indoor air, not add warm outside air during warm months. If your window air conditioner were to use outdoor air all the time, it would be much more challenging to regulate the temperature in your home.

Do Window Units Have a Lever That Lets Outside Air In?

It depends on the model of your window unit. Some do, but others don’t. A model with a lever will allow fresh air to enter your home and circulate throughout the room. Usually, this is done in fan mode, not cool mode. If you want to bring in fresh air without opening any windows, turn on your AC and use that lever to let in some outside air!

If you don’t have this option on your AC unit and can only open windows but want to take advantage of the mild spring or fall temperatures. Then perhaps use a fan instead because it’s more efficient at circulating the same amount of air as an AC—and cheaper if electricity costs are an issue for you!

Why Would You Want Outside Air to Enter Your Conditioned Space?

To keep the air that is in your home fresh. In most cases, your home’s natural cracks and crannies bring in enough air that you do not need additional ventilation to improve the indoor air quality. However, if your home does not “leak” enough air, having a ventilation source that brings in fresh air from outside and channels it into your home’s interior may help your house be more comfortable.

Another reason is odors in the home. For example, if there is an excessive amount of cigarette smoke, a wet dog smell, a burnt dinner, or some other odor in the house, you may want to bring in some fresh air to displace the air already there, getting rid of the smell.

Explained: This Is How Window Unit Air Conditioners Work

Window air conditioners work with the same concept as a full-size air conditioning system. This is done by removing heat and humidity from the air inside your home with the help of a refrigerant flowing through your ac coils. The air passes through the first coil, where the refrigerant absorbs the heat. The fan blows the air with much less heat (cool air) back into the room. The now hot refrigerant (because it absorbed the room heat) flows through the compressor and to the coil on the back of your air conditioner, the one you can see from outside. And then another fan blows air through it, releasing the heat outside, which is why the air from this side of your ac is so hot.

As your window AC does all this, it pulls the moisture out of the air. Due to the temperature quickly dropping, it causes condensation (like on your glass at a restaurant). The humidity falls down the coil and collects in the pan at the bottom of the AC. It must drain that water somewhere, which is why it must be in direct contact with an outside wall or window. This is also why you will always see window units with a constant water drip while running.

What Are The Benefits of a Window Unit?

A window air conditioner is an excellent option if you have a room that isn’t well-ventilated or if you’re looking to add AC to an area that doesn’t have ductwork to keep cool during the hot summer months. Rather than installing permanent ductwork by an HVAC professional, which can be pretty expensive and may not even be feasible in specific spaces (like the attic or basement), portable units can often cool rooms without any significant costs associated with installation. They’re also more mobile than central air systems, making them ideal for homes with varying temperatures throughout the house.

Is a Window Unit Suitable For You?

Window units are an excellent choice for people who want to stay cool but don’t have the money or desire to invest in a central air system. If you know that you’ll be staying in one place long enough to make that investment worthwhile, then it’s a good idea to go with central air instead.

But if you’re still determining how long you’ll be living somewhere or can’t afford a new system right now, window ACs make an excellent compromise. They’re cheaper than central air. They come standard with many features that aren’t available on other types of ACs—for example, they’re designed so that they can only cool down one room at once. This means that even if someone accidentally leaves the window open somewhere else in the house, it will not have much effect on this unit.

Related article: Should You Purchase a Portable or Window AC Unit?

Window ACs Cool Your Home By Removing Indoor Heat And Humidity, But They Don’t Bring In Outside Air

Window air conditioners are designed to remove hot air from the house and change it to cool air. This means that they aren’t providing you with fresh, cool outdoor air—they’re just changing the temperature of the indoor environment.

To do this effectively, window ACs have filters that can trap dust particles before they enter your living space, dehumidifiers to dry out any damp areas, and fans that blow across metal or copper coils filled with coolant fluid (i.e., refrigerant). You must keep your filter clean. As with any air conditioning system, it has to be able to move air, or it will not be able to cool it. If your air conditioner isn’t working as well as it once had, or if it keeps turning off, check your filter.


There are many benefits to having a window unit in your home. They’re affordable, easy to install and maintain, and can cool down any room in just minutes. Plus, they’re portable, so if you move or renovate one day, it will be super easy!

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