Do Window Air Conditioners Pull Air From Outside? (+9 Important AC Unit Parts)

If you have a window air conditioner, you already enjoy the convenience of having it chill your home for you. But have you ever thought about how it functions? Do window air conditioners pull air from outside, or do they simply circulate air that’s already in the room?

Window air conditioners do not use outside air to cool the inside in most cases. Instead, they take air from the room and circulate it around the space. All the chilled air blown through the Window AC unit into the room is recirculated air unless your unit has a “Fresh Air” option. If this setting is on, it will pull air from outside.

Read on to learn more about window air conditioners and how they cool circulated air to keep a room cool.

Do window air conditioners pull air from outside?

Do Window Air Conditioners Pull Air from Outside?

No, most window air conditioning units don’t pull air from the outside. Though you may see pollen and other airborne debris make its way inside, in most cases, the window AC unit isn’t the culprit.

The window air conditioner is, when operating properly, a sealed system. That means that it doesn’t allow in the air from the outside. For this, there is a fan that pulls in the air from the house’s interior. 

The air then goes through the air conditioner, where it goes over refrigerator-like parts supercoiled to increase the area of contact. The now cool air then leaves through the front of the AC while heat leaves through a heat vent at the back.

Air conditioners have air filters that prevent the machine from sucking in dust particles. The dust is usually from the air inside your house. If you were to inspect your AC’s air filter, you’d see debris that is more common in your house than from the outside.

Upon cooling the air, the fan pulls in more hot air from your house, and the cycle continues. In that way, there is a cyclic movement of air from your house through the AC and back into the house as cool air.

That’s the principle behind the cooling power of the window air conditioners. Window air conditioners operate to cool air within their environs, which is the inside of a house. Once installed, the window air conditioners operate under the same principles as a refrigerator. 

No air from outside the house is involved in the process. Therefore, if you happen to see floating particles you think are from outside, they aren’t from your air conditioner. They might have come in through the open windows or even the door.

Read Also: Can You Use a Window Air Conditioner Without a Window – What You Should Know

Window Air Conditioner Parts And Functions

The window air conditioner has different parts that facilitate its continual operation. It is simple yet complex in how it keeps the air of its environs cool even when the temperatures are over the roof. Let’s talk about the parts that enable the window air conditioner to do its work capably.


Mounted at the back of the cooling coil, the blower conveniently draws air from its environment. Firstly, the air is passed through the air filter to the cooling coil and cooled. Upon filtering the air, the blower supplies the chilled air to the room through the front panel.


The fan sucks hot air from the house then the condenser dissipates the heat into the atmosphere. This cools the air in the surrounding area. 


The strategic position of the motor requires a compact design since it holds the blower and the conditioner in place.

Filter Drier

When moisture accumulates in the refrigerant, the filter drier removes it.

Drain Pan

When the cooling coil condenses to water, the pan is used to hold the water till it is discarded.

Cooling coil

The cooling coil facilitates the exchange of heat between the air in the refrigerant and the air in the room. 

Front Panel

The front panel provides an interface where the user can adjust the settings based on the room temperature. This flexibility allows the user to set the right amount of air coming through the vent. 


The thermostat helps keep the temperature of the room at a consistent number. The scale provides the user with an opportunity to set the ideal temperature of the room. 

When the optimal temperature is achieved, the compressor stops. As soon as hot air accumulates in the room, the thermostat fires the compressor. The compressor cools the air. Keeping the compressor at optimal levels is encouraged to ensure you don’t incur substantial energy charges.

Air Filter

The air filter serves a crucial part in cleaning the air as it gets into the room. Cleaning it often is a best practice as it can clog quite easily. You don’t want to damage the machine by blocking the filter and the evaporator. 

You may also Like: Top 5 Best Thermostat Home Assistant Reviews & Buying Guides In 2021

How to Ensure Your Window Air Conditioner is In Good Shape

Although efficient in its work, an air conditioner will also need you to maintain it to ensure it is in good working order. The first thing you should do is to clean the filter regularly.

The filter gets clogged with debris from all the hot air, which might impair the working of the AC. Apart from cleaning the filter, you will also need to clean the other AC parts to ensure it is in good working order.

Cleaning the AC will also ensure you don’t get recirculating dirt back into your house’s air. Also, regular maintenance from professionals will ensure the AC recirculates cleaner air into your house.

As much as you want your house to have cleaner air, it doesn’t help if you

In addition to maintaining the AC in good shape, you will also need to be opening the windows regularly. That will go a long way in helping change the air flowing through the house as well.

Read Also: Air Conditioner Makes Loud Noise When Starting – Fix It Easily

Does Air Conditioner Ventilate A Room

An air conditioner typically removes heat from a room by cooling the air and trapping moisture. Some people think that an air conditioner also ventilates a room by blowing wind through the window and out into the open. Is this true?

The answer is no, an air conditioner cannot ventilate a room by blowing wind through the window. The reason an air conditioner can remove heat from a room is that it cools the air. When warm air is cooled, it becomes less dense and rises. This process of removing heat from a room is called evaporative cooling.

Evaporative cooling works because when warm air reaches cooler surroundings, moisture in the warmer air condenses (turns into water). These water droplets act as tiny fans and help to move the cooler surrounding air into and through the room.

How Much Of A Window AC Needs To Be Outside

Window AC units need to be placed outside of the room they are in has an outdoor temperature below 65 degrees. If the room has an outdoor temperature of 65 degrees or higher, the window AC needs to be placed on the second floor or higher.

There are various types of air conditioners, and they often differ in size appreciably. The sizes of new window air conditioners have become so diminutive that tilting the unit is almost always the best way to go. Be sure you read the instructions for the air conditioner to determine which installation method to use.

Summary of Do window air conditioners pull from outside?

Do window air conditioners pull air from the outside? The answer is, in most cases, no. The only time a window air conditioning unit will pull air from outside is if the unit contains a “Fresh Air” setting. If this setting is engaged, the unit will pull air from outside. Otherwise, a window AC unit is designed to pull circulated air from within the room for cooling.

Where does the window air conditioner pull air from?

A window air conditioner pulls air from inside the room. It circulates this air and cools it before it pumps it back into the room as cold air.

What is the air quality of air from a window AC unit?

The quality of the air from a window AC unit is typically a little higher than that of the air that’s already in your room. This is due to the air filter, which filters out airborne debris before pumping cold air back into the room.

Do air conditioners bring in fresh air from outside?

Some AC units have a “Fresh Air” setting, which allows the unit to pull air from outside to circulate into the house, but the default setting for all window units is to circulate inside air first.

Relevant Resources:

  1. How to Seal a Window Air Conditioner for the Winter – 6 Easy Steps
  2. Air Conditioner Starts Then Stops After Only a Few Seconds – 8 Effective Solutions
  3. Frigidaire Air Conditioner Buttons Not Working – Fix It Now
  4. Portable Air Conditioner Exhaust Hose Gets Hot – Top 5 Reasons
  5. How Can a Portable AC be Used as a Dehumidifier – 3 Best Steps
  6. Air Conditioner Makes Loud Noise When Starting – Fix It Easily
  7. 7 Reasons Portable Air Conditioner Compressor Keeps Shutting Off – Solutions

Let Us Know How We’re Doing!

Did this expertly prepared resource answer your question?

Do you have another question about home maintenance, home improvement projects, home appliance repair, or something else?

Get more information, send in questions and keep the discussion going by contacting the I’ll Just Fix It Myself company customer service team at at 1-800-928-1490 or Email us at [email protected]