JavaScript must be enabled in order for you to see "WP Copy Data Protect" effect. However, it seems JavaScript is either disabled or not supported by your browser. To see full result of "WP Copy Data Protector", enable JavaScript by changing your browser options, then try again.

How to Install a Window Air Conditioner

T he proficiency of air conditioning systems when it comes to lowering indoor temperatures even during the most torrid summer days, as well as their long lifespan when maintained properly and cleaned routinely makes them the go-to solution for fighting heat in homes and offices all over the world.

After you get your hands on the window AC of your dreams, the final step before you can turn it on is to install it. Calling in a professional for it will cost you money, no surprise there. But what if you were to do it yourself? If this idea sounds good, continue with us to learn what steps you must take to perform a DIY installation of the window air conditioner, saving money and gaining experience in the process.

Can You Install the Air Conditioner Yourself?

Yes, the difficulty of this project is not that high, so if you follow the instructions, you will not face issues as you install the AC. However, there is the issue of whether or not you are allowed to install it yourself or if your specific situation or area that you live in does not allow it, case in which you should hire a professional for the job.

In case you live in a condo complex or apartment, it is likely that you will be met with refusal in this sense as the reasoning is that in case you do not install it properly, it could pose a safety hazard as it might fall from the window. There are even neighborhoods that have homeowners’ association rules that do not permit DIY window AC setup.

Question: How long does it take to install it?
Answer: It does not take longer than a day to finish with the whole procedure and set up the AC, so not much time is lost before you can finally turn the AC on and enjoy its cooling effect.

What to Consider Before You Buy and Install

If you have not already bought a unit and are still looking for the best window air conditioner, then check the following aspects before you settle on a specific product:

Size the AC to the Room

Window-mounted units come in different sizes and cooling capacities, and this is the first selection determining element to look for. Only by sizing the AC to the area can you make sure it will not underperform as it is smaller than needed, nor will it be oversized, case in which it would end up raising humidity indoors. Instead, it will provide the expected cooling proficiency.

The capacity of these systems spans from 5,000 BTUs to 25,000 BTUs, the higher the BTU value goes implying that the larger the room it can cool is. As a rule of thumb, you can estimate the needed capacity by multiplying the value of the room’s square footage by 20. However, we recommend that you use the listing provided here as guidance to match the system BTU to the room surface.

Look into the Energy Efficiency Ratio

As you likely intend to run the AC as long as needed to cool the room when it gets hot, you must consider the system’s running cost efficiency as well. The best indicator for this is the energy efficiency ratio number, which is a value that typically ranges from 8 to 12 with window units. To make sure that the model you are interested in will not add much to the electric bill but rather save electricity as opposed to competitor products, pick one that is EER rated 10 or above.

Recommendation: Even if the AC does not have a minim EER rating of 10, it can still be a viable choice when it comes to energy efficiency if it comes with the right features. These energy-saving elements include variable fan speeds, sleep settings, and digital temperature controls.

Assess the Window

First, you have to consider whether you plan to install it in a double-hung window, or in a casement or sliding window. This influences the pick you make when you shop for the AC as there are different-style units designed according to the window opening manner. If you have a double-hung window, which is the more common option, you should raise the sash and measure the height and width of the opening. Use the dimensions as guidelines when you choose a unit that comfortably fits the window.

Preparing for Installation

After you install the unit, you will not open this window for who knows how long, so wash the glass now as you won’t clean it anytime soon after this. Make sure that there are no tripping hazards in the area around the window to create safe working conditions. Lastly, check for any obstructions in the opening that could hinder the overhanging part of the unit, like storm window frames or screens.

Recommendation: If you have a storm window frame, it is recommended to fasten a spacer block to the windowsill so that you lift the AC case away from it. This is the safer procedure as weather and vibrations can shift the unsecured spacer from its position, which could tilt the unit or cause it to fall.

Installing the Window AC – Step-by-Step Guide

  1. Take the AC out of the box: Be careful when you do this to not get hurt in the process. Check for all the needed pieces to be in the box.
  2. Locate the middle: Use a tape measure to determine the center of the window’s width. This makes it easier to install the AC so that the side panels are at equal distance from the window sides.
  3. Prepare the window: In case a weather strip was included, this is the moment when you should install it. The role it plays is to block air passing through the cracks. It also serves as protection for the window when you install or take out the cooling unit.
  4. Move on to the panels: Slide the panels in their respective places. Make sure to slide them inside all the way, and secure them using the screws provided in the kit. Connect all the provided screws well to avoid gaps that can let the warmth come inside, or even allow allergens and other pollutants to enter via air.
  5. Insert it into place: Pick the unit up and center it in the window. Close the window tightly on top of it. In most cases, there is a special spot on the unit where the window will slide into place when you close it.
  6. Securing with L brackets: If L brackets are included to provide added securing of the window, screw them to the top of the opened window. What the brackets do is prevent the window from being pushed up. In case they are not provided, buy them separately as they play an important role in setup safety.
  7. Attaching the panels: If you are provided padding for the sides of the open window, add it now. If it was not included, you simply need to extend the side panels until they reach the frame of the window, attach them using the included screws, and everything is sealed into place.
  8. Secure it: If the package contains screws and brackets to connect the unit to the window sill on the interior, install them now. These extra security measures come in handy, so if they are included, use them. It’s like they say, better safe than sorry.

Can You Put an Air Conditioner in a Casement Window?

Yes, there are casement window air conditioners that are specially designed for this installation, their vertical structure accommodating it. Installation differs in the sense that there are a few extra steps you must take.

First, make a wooden support base for the AC that you install on the window sill to prevent all of the weight of the system from falling on the edge of the frame, which is not structurally supportive. The height of the support base should be as tall as the height of the bottom track of the window. When it comes to its width, it should be 2 inches longer than the width of the AC.

Install the support base on the window sill, and then set up the platform assembly included in the package of the AC on top of the aforementioned base. Identify the central point of the window opening, and drive a screw in the afferent point of the platform assembly, sinking it into the support base as tight as you can.

Now, you have to go outside to put the platform assembly together as instructed in the accompanying manual. If you have a solid base, drive a screw into the siding. If not, secure a support board with plywood first, and then you can proceed to drive the screw.

Go back inside and open the window to the width of the unit, plus another 5”. Lift the AC carefully and push it through the opening onto the platform assembly. Close the sash against the side of the cooling unit, and you are done.

Recommendation: As the metal bracket that presses against the sash is the part the holds the cooling system in place, make sure that the sash is located behind the bracket for the created assembly to be secure.


Question #1: Will my AC fall out of the window?

Answer: If correctly installed and if you secured it properly, this risk does not exist. However, in case it is not secured in place or any of the installation steps have not been properly followed, this occurrence could take place. What you must do to prevent it is to secure the included accordion inserts, as well as make sure that the window stays closed.

Question #2: Can you leave it on 24/7?

Answer: Yes, you can leave it on non-stop if you so desire as it will not suffer any damage because of this. However, there are downsides to this continuous operation, the most prominent including a substantial rise in your electric bill, and less dehumidification efficiency on the system’s part.

Question #3: Should it drip water?

Answer: Yes, it is quite normal for this to happen. Some of the condensed water that forms inside it is used to cool the interior heating coils, but the majority drips outside.

Question #4: Will rain damage a window air conditioner?

Answer: No, rain will not damage the unit. However, standing water can, so if there are more than 15” of water, the electrical components and moving parts within the system may be unable to run. In case this situation arises, turn the AC off, unplug it, wait for the water to recede, and call a professional to check it before you start using it again.

Question #5: How do I get water out of my window AC?

Answer: Turn it off, unplug it, take it out of the window, and proceed to empty the pull-out pan that catches the interior-forming condensation. Afterward, locate the rubber plug and pull it to empty the unit of any water collected inside.

Bottom Line

The detailed window AC installation guide we previously provided is more than sufficient to help you out even if you are a first-timer at this job. You do not even need advanced skills, just a little patience, attention to detail, and ambition to pride yourself on a job well done at the end of the day when you finally get to plug in the unit and cool off.

Expert installation is costly, keep this in mind, so if you are the DIY type, it is not worth wasting money on a task you could easily perform on your own. To wrap it up, just see to it that you follow the steps and advice provided here religiously, and in less than a day you have had already set up the AC!

Markus Mackay
Markus Mackay
Our resident expert in all things AC-related, Markus is a never-ending source of knowledge regarding how these systems work. What makes him so savvy in this field is his direct experience that he acquired while working in sales. The connections he made during that period also came in handy here as Markus knows a lot of experts in this field. With each article uploaded, he makes sure to gather the expertise of his more experienced ex-peers as well, making sure to provide readers with reliable reviews and articles.

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.