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How to Install an Air Conditioner

Stay cool this summer even if you’re not one of the lucky ones with central air.

Debating what’s worse: Sweating the summer away in your A/C-less pad or bunking up with in-laws for three months so that you don’t have to spring for central air? For a far less traumatic and expensive solution, follow our easy guide to installing your own A/C unit.

Step 1: Get the Right Unit

You want to look for an air-conditioning unit that will fit in your window and can cool your entire room. So be sure to measure both your window’s dimension and the square footage of the room before you hit up the store. Also, you’ll need to check your outlet’s voltage. If, like most homes, you only have 110v outlets, you’ll have to stick to a smaller unit or call an electrician to install a 220v circuit. Bonus tip: If your place gets drafty in the winter, look for a window unit that also has a heat option.

Step 2: Read the Instructions

We’re not trying to be cute here. But we know that most of you won’t read the directions, so we’re gonna tell you why it’s so important to follow your specific unit’s instructions to a T: Not all A/C units are created equal and improper installation can damage your wall, unit, window or even worse, kill your neighbor’s puppy playing on the sidewalk below. Do you really want that on your conscience because you were too lazy to read the damn directions? Yeah, we didn’t think so. Although every unit differs, one specific thing to watch for when installing yours: Most units need to be tilted a bit so they’ll drain.

Step 3: Attach the Support Brackets

Do NOT skip this step. We repeat. Do NOT skip this step. Most A/C units come with brackets that attach to the underside of the unit and to the wall. Use them. This is where the whole not wanting to hurt innocent pedestrians and pets on the sidewalk below comes in: All A/C units vibrate, which means they can easily slide out of place and fall out the window or cause serious damage to your window (which will be coming out of your safety deposit if you rent). The brackets hold the unit in place and prevent all that bad stuff from happening.

Step 4: Place the Unit in the Window and Seal It

Once the brackets are properly secured, place the air conditioner on the sill and pull the window down to meet the top of the unit until it’s firmly secured in place. Then pull out the accordion-style attachments on each side of the unit. But before you pop open a beer and crank the A/C, use caulk to seal the edges of the unit (seal it from the outside too, if possible) so warm air can’t seep in through the cracks. The extra effort is worth it: Your room will get colder and you’ll save money on your energy bill (since the air conditioner won’t have to work as hard).

Nestpert: Home expert Danny Lipford hosts the TV show Today’s Homeowner and the radio show Homefront. His website,, features thousands of home improvement articles and videos.

-- Erin Walters