How to Install a Window Air Conditioner

The mercury is rising and the humidity is making it feel even hotter. It's time to install that air conditioner! If central air conditioning is too expensive to consider, then a window unit should be enough to cool things down. Once you have the air conditioner home, it will take just minutes to install it in the window...and you'll be on your way to a cool night's sleep!

Install a Window Air Conditioner

Install the mounting brackets onto the windowsill. Screw one end into the sill. Adjust the center screw on the bracket to level the air conditioner.

Open the window fully. Slide the air conditioner over the sill and onto the mounting brackets. Close window to the top of the air conditioner casing.

Pull out the extensions on either side of the air conditioner until they touch the sides of the window. Once fully extended, drill small holes into the window sash and use screws to fasten each extension to the sash.

Secure the sashes to each other with angle brackets, if brackets are supplied by the air conditioner manufacturer. Use a strip of foam to insulate the gap where the two sashes meet to prevent the cool air from seeping outside.

Make sure to tilt the air conditioner slightly away from the window to ensure proper water drainage. Caulk the unit outside around the air conditioner. Then plug in the air conditioner. It's now time to cool off!

Things You Will Need

  • Measuring tape
  • Level
  • Foam strip
  • Screws
  • Screwdriver
  • Drill
  • Waterproof caulk
  • Caulking gun


  • Measure the room to be cooled to ensure that you're buying an air conditioner with the proper cooling capacity.
  • Make sure the window is in good condition to support the air conditioner. A double hung window near an electrical outlet is best.
  • Always follow the instructions in the manufacturer's manual accompanying the air conditioner.


  • Never use loose objects, such as a block of wood, to support the air conditioner.

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