Air Conditioners

Can Window Air Conditioners be Installed Through the Wall?

window ac unit lg

Window and wall air conditioners are a great way to cool a room or a small house in situations when central air isn’t an option. You can even set up several of these units throughout your home and do away with a central air conditioner. 

You can install window air conditioners through the wall. The great thing about window air conditioners is that you can use the same air conditioner for window installation or wall installation.

Having said this, you will need to make several adjustments to your window air conditioner before installing it through a wall. Installing a window AC through a wall is dangerous unless you make the proper modifications. 

The convenience and easy window AC installation are tough to compete with. In this article, we’ll look at how to convert a window AC to a wall one. We’ll also look at the advantages of both methods and so much more. If you have questions about window air conditioners, you’ve come to the right place. 

What is the Difference Between Through the Wall & Window Air Conditioner?

A window air conditioner is often the same as a through-the-wall air conditioner. The significant difference is how you vent the air conditioner and ultimately install it.

There are advantages to both, but it’s primarily your personal preference determines where you ultimately install your AC. It sounds self-explanatory, but window air conditioners are installed in a window, and wall ACs are installed through a wall.

  • Window air conditioners: are vented through the back and sides of the unit to provide as much airflow as possible.
  • Through-the-wall air conditioners: are vented through the back only because you place them in a wall sleeve going through the wall. 

If your air conditioner comes from the store designed for wall installation, you’ll have to convert the venting setup to accommodate a wall installation.

A window air conditioner that vents out of the sides and back of the unit are a fire hazard when installed through the wall. Side vents on a through-the-wall air conditioner would produce intense heat that could overheat the system or be a fire hazard. 

For this reason, you must know what kind of air conditioner you’re getting before you install it. Both air conditioners are interchangeable, but you must make the necessary modifications first.

While the venting needs to be modified, you don’t have to do anything with the condensation drain. Both units will drain the same way, through the bottom or back of the device.

How Do You Install a Window Air Conditioner Through The Wall?

Installing a window air conditioner into a wall is possible but can be difficult. The most important thing to remember for your safety and the safety of the AC itself is to change the venting system from the sides of the unit to the back only. Venting an air conditioner out the sides will cause the unit to overheat and possibly result in a fire hazard. 

Here is a step-by-step process of how to install a window air conditioner on your wall:

1. Convert the Venting From the Sides to the Rear of the Unit

Once you’ve decided to install your window air conditioner through the side of your wall, the first step is to convert the venting.

Most window air conditioners come with the option to use either form of venting, and you can follow instructions with the air conditioner to switch from one to the other. If the companies did not provide that part, you could readily purchase them at any hardware store. 

2. Cut the Drywall to the Proper Dimensions

Once you pick the location for your air conditioner, the next step is to cut the hole through the drywall inside your house. When cutting the hole, ensure that you don’t succumb to the temptation of cutting the exact dimensions of the sleeve itself.

You’ll want to leave 4-6 inches around the sleeve’s outside to accommodate the header and footer that you’ll install later. 

3. Remove Any Excess Insulation Inside the Wall

All outer walls of your home should have insulation to protect against high and low temperatures. Remove this insulation to continue the installation process. 

Make sure to wear protective gear, as this could be harmful to put near your body. This gear includes gloves, a mask, and eye protection.

4. Frame Your Header & Footer for the AC

Next, you’ll construct a header and footer to frame around your air conditioner sleeve for added support. You’ll also need something solid to reattach the drywall inside your house.

You’ll need to run your lateral boards from stud to stud and connect the vertical panels perpendicularly to those. 2x4s or 2x6s are suitable for this task. 

5. Cut the Outside of Your House to Match the Sleeve

It’s important to note that you don’t want the outside hole to match the inside but rather the air conditioner sleeve itself.

You want the hole to be large enough for the sleeve to fit through it and only need a bead of caulk or spray insulation to seal. The best way is to drill holes from the inside to the outside, marking the location of the sleeve. 

6. Install the Sleeve for the Air Conditioner

When installing the air conditioner sleeve, there are several things to keep in mind. You will want to line the outside of the sleeve up with the outside hole. Taking these steps will make for a neat look on the outside.

You’ll also want to install the sleeve with a slight downward slope to ensure that condensation water runs outside and not inside your home. 

Once you line everything up just as you want, fasten the sleeve to the constructed frame. The unit secures by running screws through the sleeve and into the wood frame you’ve built.

However, make sure not to put screws through the bottom of the sleeve, as this will only create holes for water to drip through and possibly leak into your house. 

7. Insert the Air Conditioner into the Sleeve

Now comes the easy part, actually installing the air conditioner. The sleeve has a specific design to accommodate your AC unit, so this should be a seamless process.

Once the air conditioner fits inside the sleeve, it’s time to conduct a quick test to ensure everything is working. If everything checks out, unplug the unit and continue with the installation. 

8. Seal Any Gaps Around the Air Conditioner 

Sealing gaps is especially important for the outside of your house. It’s impossible to perfectly cut the hole in your siding and create an airtight seal, so you’ll have to use caulk or insulation.

Sealing is vital to keep rain and snow from leaking and keep warm or cold air out. Silicone caulking or spray insulation is your best and easiest option for this step. 

9. Repair the Drywall on the Inside

Because you had to cut the hole on the inside to accommodate the framing, there will be visible wood when looking at the air conditioner.

If you were careful when you cut the initial hole through the drywall, you could use leftover pieces to make necessary repairs. If not, you can purchase drywall at hardware or a home improvement store and cut to the essential dimensions. 

10. Add the Finishing Touches to the Inside Wall

If you want to be fancy with your air conditioner, there are unique trim pieces you can fit around it inside. Proper alignment will make for a neat and aesthetically pleasing look to your air conditioning unit on the inside and outside. 

There you have it, how to install a window air conditioner through your wall. It’s not an overly complicated process if you have the tools and skills necessary, but it can be time-consuming.

If you don’t feel comfortable, plenty of qualified construction workers and HVAC technicians are capable of completing the job. 

Can You Put a Window Air Conditioner in a Room Without a Window?

There are ways to install a window air conditioner in a room without a window. It might sound counter-intuitive, but there are ways to do this. It works similarly to how a portable air conditioner does.

The two most difficult parts of this process are figuring out how to vent the air conditioner and drain the condensation. 

Venting a Window AC Unit

The air from the vent creates high amounts of heat to offset any cooling the air conditioner produces. If you want your AC to be of any help, you will need to find a way to redirect that heat outside of the room you’re trying to cool.

Venting can be done through a window, the attic, or a wall if you want the air conditioner to be a permanent fixture. 

The fumes from the venting aren’t harmful like those of a furnace or water heater. They’re simply counterproductive. For this reason, you can even redirect the venting to a closet or nearby room. The preferred locations, however, are outside or into the attic. 

If your air conditioner has to vent out of the back of the unit, you can frame a vent cover to encompass the rear of the AC.

You will then need to cut a hole in the cover and attach an insulated, flexible duct. You will then run the other side of the ductwork through a window or into an attic to redirect the vent heat to a suitable location. 

Catching the Condensation to a Good Location

The other tricky part about installing an air conditioner is figuring out how to catch the condensation and redirect it to a suitable location.

You can do this by attaching a hose from the condensate point on the air conditioner and running the other end to a drain. Make sure that you have a steady, downward slope on your hose. Otherwise, you’ll have a wet mess on your hands. 

To capture excess water, you can also set a pan or bucket beneath the air conditioner. You’ll have to remember to dump the bucket regularly, but it’s similar to how a dehumidifier works. 

Do You Need a Sleeve for a Wall Air Conditioner?

If you install your window air conditioner into a wall, a wall sleeve is essential to its proper operation. A sleeve supports the heavy air conditioner that drywall and siding alone aren’t strong enough to hold.

A wall sleeve will also enable you to make an airtight seal around your air conditioner. Airtight seals are essential both on the inside and outside of your house. 

A wall sleeve isn’t challenging to install as long as you follow the above directions. Cut your hole the right size and frame 2x4s or 2x6s around the sleeve, and your task is almost complete.

Wall sleeves take a little extra time on the initial installation, but they are well worth it in the long run. The last thing you want is your air conditioner to fall through your wall, damaging both the air conditioner and your house. 

How to Install a Window Air Conditioner 

Window air conditioners are much easier to install than wall-mounted ones. Choose the window you want the air conditioner to sit in, open it, and set the AC out through it. Set it up so your air conditioner is tilted downward to direct the condensation outward. 

Also, make sure that you seal around the air conditioner and gaps in the window frame. You don’t want a permanent seal because you want to remove the AC during winter. Foam pads or other removable forms of insulation are ideal for this type of setup. 

Choosing the Best Air Conditioner For You

When deciding what kind of air conditioner is right for you, you should keep several things in mind. Window air conditioners aren’t permanent; you can remove them each winter or when you’re not using them.

On the other hand, through-the-wall air conditioners are permanent, and you will set them in place for the duration of the air conditioner’s lifespan. 

This type of air conditioner offers the advantage of not using up any windows, which means you can open and close them as needed.

Some rooms only have one window, and you might not want to block it up with an air conditioner. The major drawback of wall air conditioners is the complicated installation.

Here are 2 of the crucial things to consider before buying an air conditioner:

1. Cost Comparison 

The overall cost of the air conditioner itself is very similar across the board. Because both types of ACs are interchangeable, there is very little difference in what you’ll pay upfront.

The higher cost comes when you install the unit. Through the wall, air conditioners can sometimes require professional installation, which means they will be more expensive in terms of upfront cost. 

Cooling Power 

Because the air conditioners are very similar or even the same, there will be little difference in how effectively they cool your house. A window air conditioner is more difficult to seal completely, so in this way, a through-the-wall unit is ever so slightly more efficient. 

Final Thoughts

Ultimately, deciding to install a window air conditioner in a window or through a wall is entirely up to you. A room doesn’t have a window in certain instances, leaving you with the wall as your only option. Most times, however, you will have the chance, depending on what you prefer. 

Window air conditioners are easier to install, and you can remove them when not in use. Through-the-wall air conditioners are permanent fixtures that require little maintenance but are much more challenging to install. By weighing the pros and cons of each, you should make the best decision for your situation. 


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.