Tools and Materials
Products, costs, availability and item numbers may vary online or by market.
Know Before You Buy a Window A/C
Before you learn how to install an A/C unit in a window, you should gather some basic information.
- Determine the window where you’ll install your A/C. If there’s no 3-prong outlet nearby, you’ll need an extension cord labeled for A/C use.
- Check the load on the circuit you plan to use. This will help you avoid a tripped breaker or blown fuse.
- If the circuit is also powering other devices, even simple ones such as a hairdryer, you should consider adding a dedicated circuit or choose another window near a different circuit.
- Determine whether your window is a sliding, double hung or casement style. Most units work only in double hung windows with a bottom sash you can raise and lower. Also, measure the width and height of the window opening to confirm whether an A/C will fit.
- Not sure what type of window you have? Check out our Window Buying Guide.
- Decide how much additional insulation and rain protection you’ll want to add around the window beyond the A/C’s side curtains. For example, pieces of white expanded foam insulation will help keep the weather outside.
- Consider what side of the house your window faces. Does the wind typically whip rain against that side of the house? Adding more barriers will keep water from coming in.
- West-facing windows may catch more sun and force the A/C to work harder.
- Think about replacing curtains or drapes around the window with privacy blinds or shades or adding curtain tie-backs to keep the A/C area clear.
How to Install A Window A/C Unit
Window A/C installation requires some preparation to the window area, but you’ll be rewarded with low-maintenance comfort all season long. First, inspect the window and sill to make sure it’s in good repair. You’ll also want to clear the area around the window and leave yourself plenty of workspace with no tripping hazards.
Check for obstructions in the window opening. A storm window frame or screen might interfere with the overhanging part of the A/C on the outside. Either remove the storm window and frame or fasten a spacer block to the windowsill to lift the A/C case away from the obstruction. After installation, you probably won’t remove the unit until the end of the season, so now’s a good time to clean the glass inside and out.
Choose the Right Size and Type of Window AC Unit
When selecting a window A/C unit, a key decision is the size of room in which you are installing the air conditioner. A too large unit won’t eliminate enough humidity from the room, leaving it with damp feeling air. An undersized model will not be able to adequately cool the room, forcing it to work harder than it should.
To find the proper size of A/C window unit you will need, you need to know the square footage of the room. To find this, simply multiply the room’s length by its width. Example: a 10-foot by 10-foot room will have 100 square feet to cool.
With the square footage, compare to the window air conditioner’s British thermal unit (BTU) rating. A BTU rating indicates the amount of heat an A/C can remove from a room. The larger the room, the higher the BTU rating needs to be.
Here are some general guidelines for choosing the appropriate BTU for your room size:
- 150 to 350 square feet: 5,000 to 8,000 BTU
- 350 to 550 square feet: 8,000 to 12,000 BTU
- 550 to 1,050 square feet: 12,000 to 18,500 BTU
- 1,050 to 1,600 square feet: 18,500 to 25,000 BTU
Also, take into consideration if your room is in the shade or the sun. Please note that as the BTU rating increases, the size and weight of the unit will also increase.
6 Steps for Installing a Window A/C Unit
Maintaining Your Window A/C Unit
One of the benefits of installing an air conditioner window unit is that it can cool just where you want it without adding on to the whole house system. Home additions and converted spaces are perfect places to add cool air without major remodeling. To keep your installed A/C unit running at its best, routine upkeep is required.
Window A/C unit maintenance is pretty simple to do:
- Clean or replace your air filter every 30 to 90 days. Many units today have a permanent filter that doesn’t need replacing, just a regular cleaning. Simply remove the filter, brush away any lint or dust build-up, and then wash with warm water and mild dish soap. Make sure the filter is completely dry before reinstalling.
- Inspect the outer coils to make sure that they are clean from dirt and debris. You can use compressed air or a soft bristle brush and household cleaner to remove any dirt from the coils. This step is important if your unit has any outside plants or shrubs that may be in contact with your unit.
- Check to ensure that your weatherstripping is intact and doesn’t have any cracks or is missing pieces. If your unit is a permanent install, consider using caulk to seal any gaps or holes.
Frequently Asked Questions
Here are answers to some of the most commonly asked questions on installation of air conditioners in windows.
Can I Install a Window A/C Unit Myself?
Installing air conditioners in windows as a solo project can be done, but it is highly recommended to have some assistance when doing this project. Some window units can be heavy or awkward to maneuver when lifting into the window space. Having a helper can make the install safer and easier.
What Is the Correct Way To Install a Window Air Conditioner?
The correct way to install a window air conditioner is to follow the manufacturer’s installation instructions. Along with a helper, this can usually be done in a couple of hours. By completing all of the installation steps, you should have a safe and dependable set up for your home.
Do Window A/C Units Need To Be Screwed In?
In order to have a secure installation, window A/C units must be screwed into the window sash along with fastening the side panels to the window frame. For added safety, an air conditioner window bracket can be used to support the weight of the unit from the outside.
Do Window AC Units Plug Into a Wall?
Window A/C units can plug into wall outlets that accept a 3-prong plug. If your power cord isn’t long enough to reach an outlet, then you can use an extension cord that is approved for use with an A/C unit.