How to Install a Window Air Conditioner

Even though a window air conditioner is relatively easy to install, it is still important to follow these simple tips for installing your unit. These air conditioning units are not only easily installed, they also represent a significant savings over the cost of the construction of a central air conditioning unit within a home.

While it is important to know the basics of how to install a window air conditioner, it is also important to refer to the manufacturer’s instructions for any specific steps required for that particular unit.

Choosing the Ideal Space for the Unit

In order to ensure the efficient function of the air conditioning unit, it is important to select the ideal space for it. This can be done by selecting a space that is as close to the center of the room as possible, close to an electrical outlet, and away from the heat of the sun.

If it is not possible to find a location that possesses those three factors, opt for a space that is in a shaded spot of the house, as prolonged sun exposure will cause the unit to use much more energy to cool the room. If an extension cord must be used to reach an outlet, it is important that it has been rated for use on an air conditioner.

One more important step before you buy a window air conditioner is to review the unit specs to see what the minimum window width and maximum window width requirements are. If your window is too narrow or too wide, the window air conditioner will not fit properly.

How to Prepare the Window for Installation

Before the unit is placed in the window for use, it is important that the window is inspected for any damage or rot. Failing to do so may result in a window that becomes further damaged by the unit if the window’s structural integrity has been compromised. Any damaged window sill could also result in serious damage or injury if the air conditioning unit falls out of the window. If there is any damage or rot in the selected window, it must be repaired before the window air conditioner is installed.

If the window is free from damage or has already been repaired, it is wise to remove any obstacles that may impede installation. Any storm windows or screens should be removed and stored someplace safe prior to installation. It is also wise to enlist the help of someone else due to the unwieldy nature of window air conditioning units.

Bracket Installation

There are units that may require the use of brackets as a part of the installation process. These brackets are installed outside of the window, attaching to the house. There may be some adjustments in the leveling that need to be made, so it is important that the owner’s manual is referred to during the installation process.

Installing the Unit in the Window

When it is time to install the unit in the window, the window should be opened just enough to allow the unit to fit inside. The accordion panels, which are located on the sides of the unit, should not be extended until the unit has been secured in the window, as this may cause difficulties in achieving ideal placement if they have been extended. The angle that the unit is ultimately positioned in should be done in accordance with the instructions provided by the manufacturer, since many units are different in this regard.

Once the unit is in place in the window, the accordion panels can be extended. These panels can then be screwed into the bottom sash of the window. Most window sashes will have holes already in place, but if they do not, drill a pilot hole in the window before screwing in the accordion panels. This will help prevent the wood from splitting.

It is important during this process that the window sash does not move upward. Many units will include brackets that are explicitly for this purpose, though there are alternatives that can be used if the unit is not equipped with these angle brackets. A 2×2 inch stock can be cut to be wedged between the top of the bottom window sash and the top frame of the window.

As mentioned earlier, an important step before you buy a window air conditioner is to review the unit specs to see what the minimum window width and maximum window width requirements are. If your window is too narrow or too wide, the window air conditioner will not fit properly.

Insulating and Weatherproofing

Most units will include weatherproofing strips to help combat the fact that there is now an opening between the two panes of window glass. If there is no weather stripping, this can be easily found at your local hardware store. The weather stripping should be used to seal this gap, and if there is a great deal of wind or rain, it may be wise to use caulk to further seal the opening. Following these important guidelines will not only help keep the elements out of your home, but also keep your cool air from leaking out.

Through-The-Wall Window Air Conditioners

Through-the-wall window air conditioners are window air conditioners that can be installed in applications other than windows. These window air conditioners can be installed into spaces such as walls using a special sleeve that comes with the unit. If you are looking for an application other than a window, be sure to look for these types of models. Also, be sure to make sure the unit you buys comes with all of the necessary sleeve components for the installation.

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Kara Zorn

Kara Zorn

Kara Zorn is a wife and working mom who loves life hacks that help her schedule allow for as much quality family time as possible. She enjoys cooking with locally sourced food and produce and recently took up brewing Kombucha.


  1. My landlord said he’d help us install the air conditioning unit in our house, but he’s not going to be back in town for a week and it’s warming up. I figured I could try to do it myself, and this article definitely helped me to understand how to do it. I’ll be installing it in the window with the help of a friend, thank you for the advice.

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