How To Install a Window Air Conditioner Step By Step

How To Install a Window Air Conditioner Step By Step

You have bought a new window AC unit (or you haven’t and should check the best window air conditioners reviews) and you have to install it. Installation of a window air conditioner is very easy and there is no need to hire professionals for this job. Of course, if you have any health issues with your back or hands you can simply rely on a team of customer services. They definitely help you and solve your problem however you will have to pay for it up to $150.

For those who believe they are handy and can make this job, I prepared a Guide on how to install a window air conditioner step by step. The process of installation takes only a few minutes. You don’t need to have lots of special tools or skills. Follow our guide together with instructions from a producer of the unit and will stay cool very soon!


Before you start it’s crucial to find out if the unit is suitable for a window you have chosen. You have to find out if your machine meets three requirements.

The majority vast of this kind of unit has a power cord 5 or 6 long. It means you have to double-check the distance between outlet and windowsill and make you sure it’s enough. Otherwise, your effort will be useless, you will have to reinstall the unit and put it on a different sill. It’d be wasting time and effort.

Once, you know the position of a window is suitable you have to double-check the window itself. Measure the width of a window if you didn’t do it before. The unit can’t be larger than the width. When you find out your unit is smaller it’s perfect because you can fill the gap by using the accordion panel. The problem occurs when you have a unit larger than the width of a window. The unit doesn’t fit. You have two possibilities for what to do then. You can use it for another window which is wider than the first one. Or you have to buy a smaller unit.

When we know our new air conditioner is suitable for a chosen window and it will be close to the outlet we can move on. The last preparation phase includes double-checking if the machine you have bought it’s suitable for a type of window. To clarify, there are two versions of AC unit one for double-hung windows and another for casement windows. You have to purchase an appliance suitable for a type of your window because you can’t change them. And this guide on how to install a window air conditioner step by step would be useless.

Material And Tools You Need

Since the installation is pretty easy you need some additional material and tools to make it smooth as soon as it’s possible.

  • Window AC unit
  • Screwdriver
  • Screws
  • Drill
  • Measuring tape
  • Pencil
  • Angle brackets
  • Window padding
  • Knife (useful for some models)

You will appreciate another pair of hands however you are strong enough to put the machine on a window without any help. Consider asking a friend to help you with this job.

Step 1: Take Out the Unit

Take the unit out of the box and be careful because the rear part of the appliance can be sharp. According to the instruction from a producer make sure in a box there are all necessary parts.

According to instructions double-check if you received all parts in the box and screws needed for installation. It’s possible you will have to buy some screws because a producer doesn’t attach them in a box a part of a packaging. If so, it’s time to go and purchase them.

Step 2: Measure a Window And Find a Center

In this step, you use the measuring tape and a pencil. Precisely measure the width of a window you want to install the unit in. Then, mark the center of a window by using a pencil.

It’s a very important part of our work because it helps us to build in the accordion side panel equally.

Step 3: Prepare the Window for Installation

how to install a window air conditioner step by step

Open the window you used for marking a center. Some models of window AC units are sold with a weatherstrip. Install the strip according to the instruction very carefully.

The strip is very useful in many ways. It protects the window against the air that could blow through tiny cracks. Another brilliant advantage of this strip is protection for possible damage during installation and de-installation of the appliance.

If a package of your bought machine doesn’t contain the weatherstrip you should consider getting it before the installation. It’s a worthy little helper.

Step 4: Secure Accordion Side Panels

how to install a window air conditioner step by step

The window is prepared and the unit is almost ready. Moving on in our guide on how to install a window air conditioner step by step. Now, carefully slide the accordion side panels into the right place on your machine. Strictly follow the instructions in a manual given by a producer.

Fasten the panel by using screws. Use all of the attached screws or all the screws you bought and they’re needed according to the manual. Many people want to save some of them and don’t use them all. The consequences are terrible as there are gaps where the air can flow inside the room, also dust, dirt, pollen, and allergens can get in. Remember your window is open just filled by a window air conditioner. Therefore, you need to fill the gaps and protect your home.

Step 5: Put the Window Air Conditioner on the Sill

how to install a window air conditioner step by step

As we noticed it’s much better to have a friend to help you. And this is the moment when the help you will appreciate as much as you can regarding safety. It this step, you and your friend have to put the unit on a windowsill and fasten it properly.

Take the appliance together with your friend and put it onto the sill. Then, carefully close the shut on the top of a machine. Since the major part of the AC will be outside we recommend one person hold the unit while the second one is closing the window.

Step 6: Install Angle Brackets

how to install a window air conditioner step by step

We are almost there! You did the hard work and now we have to focus on fastening everything on a place.

Since every model is different the accessories in a box can vary. But the vast majority of the machines are sold together with angle brackets (also called L brackets). If the appliance you bought doesn’t include the brackets you should buy them in advance.

The brackets must be installed to prevent the window shut from being pushed up. Fasten them by using screws.

Step 7: Fill the Gaps by Attaching Accordion Side Panels

how to install a window air conditioner step by step

If in the packing of your unit included window padding it’s a great idea to apply them on both sides of the open window. If you haven’t received the padding no worries. Simply attach the accordion side panels to the frame of a window. Fasten them by using screws provided by a manufacturer.

Now we fill the gaps and prevent the air blow inside a room as an important part of our guide on how to install a window air conditioner.

Step 8: Fasten The Window AC Unit on A Sill

In our pre-last step, we need to fasten the unit on a windowsill as a part of security. Some producers provide the brackets and screws for this reason. Follow the instructions from a manual.

If in a box of your chosen unit there were no screws and brackets for this purpose then the producer of a unit belongs to a group of people who consider this as an extra security step.

It means we’re done. Great job!

Step 9: Switch on The Unit And Double-check It

Plug the machine in an outlet and switch it on. The goal of this step is to find out if everything was fastened properly, the unit is working, and no air blows through the side panels. If everything is working then you can enjoy the comfort and cooled room. Sit down and relax.

The Bottom Line

I believe my ultimate guide on how to install a window air conditioner step by step helps you and the installation was easy for you. According to differences among brands and models, you can deal with some small differences but in general, the steps are the same. Now you can check how to make AC unit smart.

The installation is easy however, it’s better to have a friend who can help a bit and you don’t put such an effort. Since the installation process can make everybody you don’t need to hire a team of professionals and pay for their services. Just follow our guide and instruction given by the manufacturer.

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