How to Install an Air Conditioner in 5 Breezy Steps

Your first step is to make sure the AC unit sits level in the window opening. Believe it or not, not all windows are actually level, particularly when measuring from front to back. To solve this problem, add a wood block or two between the windowsill and the future home of the air conditioner. Add one in the front to start and make a measurement, adding another toward the back when necessary.

Standard 2x4s cut into smaller pieces work well for this, but it truly depends on what is going on with your windowsill and how even it is already.

In an ideal world, all of the cool air stays in your home, while the hot air jettisons outside. To assist with this, weatherstrip the window and the area immediately surrounding the AC before going ahead with the installation. Some AC units ship with weatherstripping of some kind, but a standard 1-¼” x 1-¼” foam weatherstrip works great here.

Cut, peel, and stick the strip as you normally would, making precise cuts so it fits the windowsill to a tee. Affix one strip to the windowsill, another to the bottom of the window, and a final strip on top of the air conditioner.

Before placing the window unit, make sure there are no people, pets, or delicate objects on the ground below where your AC will go. It’s also wise to ask someone to assist you for the actual AC placement. Window AC units are notoriously heavy and easily slip from your grasp, careening to the ground in a thunderous crash. Start by opening the window and liting the air conditioner into the window opening until the accordion wings are completely even with the window jamb. This should center it within the opening. Lower the upper window down on top of the AC and hold it in place. Finish this step by expanding the air conditioner wings so they close the gap on each side.

Affixing the AC to the window is an optional step, as once the AC is correctly placed and the upper window is pushed down into the center, it will hold. If you want extra security, however, affix the AC to the window by inserting some screws through the holes in the wings. This does put holes in your actual window, so exercise caution here, go slowly, and use the correct type of screw. Four screws, two on each side, should finish it off.

Window AC units require a designated 20-amp circuit. If the plug struggles to reach the nearest outlet (window AC plugs are on the shorter side,) feel free to connect it to a heavy-duty appliance cord and run that cord into the outlet. Avoid low-grade extension cords and surge protectors. Give the AC its own spot in the outlet to minimize any chances of overloading the system.