How to Use a Window AC Without a Window

window air conditioner

Using a window air conditioner (AC) without a traditional window is possible with some creative solutions. If you find yourself in a situation where window installation isn’t feasible, consider the following ways to use a window AC without a window:

  • Sliding Glass Door Kit: Invest in a sliding glass door installation kit specifically designed for AC units. This kit allows you to create an opening in a sliding glass door to install the AC unit securely.
  • Through-the-Wall Installation: If you have a suitable interior wall, you can install the window AC unit through the wall using a wall sleeve. This method may require professional installation to ensure a secure and weather-tight fit.
  • Ventilation Hose: Use a flexible ventilation hose or duct to channel hot air from the AC unit to the outdoors. Create a small opening in the wall, floor, or ceiling where you can attach the hose. Seal the gaps around the hose to maintain energy efficiency.
  • DIY Window Bracket: Build a custom window bracket that attaches to the frame of a door or any available opening. This bracket can support the AC unit securely while allowing it to vent hot air outside.
  • Portable AC Unit: Consider using a portable AC unit that doesn’t require a window installation. These units come with a hose and window adapter kit, allowing you to vent hot air through a nearby window or a specially designed opening.
  • Attic Installation: In some cases, you can install a window AC unit in an attic space with suitable ventilation and ductwork to channel hot air outside. Ensure proper insulation and weatherproofing.
  • Professional Assistance: For more complex installations, such as through-the-wall setups, seek professional help to ensure a safe and efficient solution.

What Happens if You Don’t Put a Window AC in a Window?

To understand what will happen if you use a window AC in a room without a window or without putting it in a window, you need to first understand how window air conditioners work.

Window air conditioners work just like other types of air conditioners. They have an evaporator coil, compressor, condenser coil and use a refrigerant/coolant for cooling.

Air conditioners work by removing heat from indoor air and releasing it outside. That is the reason why air conditioners have an indoor and outdoor unit. The indoor unit absorbs heat from the air while the outside unit dumps it to the surrounding.

While window air conditioners are made up of a single unit, one part of the air conditioner is designed to be indoors while the other part is designed to hang on the outside of the house. That way, the unit can absorb heat from the indoor air and dump it outside.

outside of window AC

The evaporator coil is found on the front of the unit, that is the side inside the house. When the fan pulls warm air from the house, it fast goes through the evaporator coil which contains a cold liquid refrigerant flowing through it.

The refrigerant absorbs heat from the air and that is how the air is cooled. The cooled air is circulated back to the house.

After absorbing heat from the air, the refrigerant evaporates and flows out to the compressor where it is compressed to increase its pressure. An increase in pressure also increases the temperature of the refrigerant more than the outside.

When the high-pressure refrigerant enters the condenser coil, it loses heat to the surrounding thanks to the temperature difference. A fan makes this process even quicker. That is how window air conditioners exhaust hot air to the outside.

Apart from cooling, window air conditioners just like other ACs will also dehumidify the air. That happens on the evaporator coil’s surface.

When the warm is cooled, its potential to hold moisture reduces and hence the moisture in the air condenses and drains in a pan at the bottom of the unit. The pan also has an outlet near the rear of the unit to make sure that the water actually drains outside the house.

Some window ACs use the condensate to cool the hot condenser coil. After cooling the coil, the condensate evaporates and is exhausted as vapor. Such units don’t drain away a lot of condensate.

Now that you know how a window AC cools the indoor air, exhausts the hot air and drains the condensate, what do you think would happen if the window AC is used without a window?

Using a window AC without a window means that the indoor air would first be cooled, but since the unit is not vented, the condenser would release the heat back to the indoor air. The air would therefore go through cool and hot cycles and since the unit is releasing its own heat by just running, it would make the indoor air even warmer.

Another thing to remember is that the unit would have no way of draining the condensate outside. A window AC will therefore flood the floor with water if it is used without a window.

How to Use a Window Air Conditioner without a Window

If you can find a way to vent a window air conditioner, you can use it even in a room without a window. Again, these methods will not work as well as a properly installed window AC (they will even be more expensive due to low efficiency) but the unit will cool the room anyway.

The following are the different methods of using a window air conditioner without a window:

1. Convert the Window AC into a Portable AC

Portable AC

A portable air conditioner is a portable version of a window AC. All its components are housed in one unit and are located inside the house.

To vent the hot air outside, portable ACs have an exhaust hose which is vented out through the window. There are also several ways to vent a portable air conditioners without a window, which are what you should do with a window AC.

As I mentioned earlier, window air conditioners release hot air through their rear. To use a window air conditioner like a portable AC, you need to fabricate some sort of a funnel big enough to fit the rear of the unit.

You would then use duct tape to seal around the funnel then connect an exhaust hose to the funnel and vent the unit through the attic or a door leading outside or another room where the excess heat would not be a problem.

Some people use storage bins, cardboards or even trash bags to make the funnel but I would prefer to fabricating one using sheet metal. Another option would be using a split AC cleaning bag like then one shown below. Cut out the water pipe and connect it to the exhaust hose.

It is important to make sure that you do not cover the side grills since those are the ones responsible for air intake. Covering them will result in overheating of the condenser coil.

Note: This setup will work like a single-hose portable air conditioner. What that means is that since the unit will be pulling out air without replacing it, there will be negative air pressure created inside the room.

Depending on the room you are cooling, you may want open a door to bring in fresh air from other rooms or even drill a hole next to the unit to bring in air from outside. Some people also use 2 hoses in parallel. One hose exhausts the hot air while the other one brings in equalization/makeup air.

Another thing you will want to do is to carefully drill a hole at the bottom of the unit. That is the hole the condensate will drain out through. You may then place a bucket underneath to collect the condensate or connect a drain hose and direct it outside or to nearby sink.

As you drill the hole. You need to be very careful not to puncture the condenser coil. Use the push-pull technique. That means holding the drill with both hands where one hand will be pushing and the other pulling.

Note: The hole should be drilled underneath the back of the unit and also remember to place the AC in such a way that it is tilting backwards just like it does in windows. That will allow all the condensate to drain out.

2. Place the Window AC Outside

Another thing you can do is to place the AC outside the house and duct the cool air inside. I haven’t tried this technique myself but a friend recommended and it makes a lot of sense.

If you can vent hot air out outside, what would prevent you from venting cold air indoors? Nothing. It is just like how evaporator coils in central ACs are located in basements yet cool air can be ducted upstairs. This method also solves a lot of the problems with having the AC indoors.

To start with, you don’t have to worry about warm air being circulated back to the house. The only thing that will enter in the house is cool air.

You also don’t have to worry about how the unit will drain. It will drain on its own outside and you don’t even have to drill a hole at the bottom of the unit.

This method is good for your house’s aesthetics. Window ACs need to be placed on an elevated surface and also need a bucket to drain the condensate. The exhaust hoses are also not pretty to look at.

3. Convert it into a Through-the-Wall AC


Through-the-wall air conditioners look very much like window air conditioners only that they are installed in a room’s wall and not window. A hole is made through the wall and the AC is then installed, where part of the unit will be inside the house while the rear will be outside the house; just like in window ACs.

Through-the-wall air conditioners come with a sleeve which fits in the hole on the wall and then the AC unit slides through the sleeve. These units are more efficient than window ACs.

You can cut the wall in an exterior wall or a wall leading to another room where the excess heat released by the unit would not be a concern. However, not all walls are a good candidate for this conversion.

The wall should not be too thick. Through-the-wall ACs are designed with wall thickness factored-in but not window ACs. If the wall is too thick, it can block outside air vents causing the AC to overheat and turn off and even get damaged.

Again, make sure that the unit slants towards the outside. This will ensure that the condensate will drain out and not in the house or even worse soak up and damage the wall.

To prevent cool air from leaving the house and warm air from entering, you will need to seal all around the AC. Sealing increases the efficiency of the unit and also prevents insects from entering the house. Expanding foam or caulk can be used.

If you can afford to make a hole in any of your walls, this is usually the best method of using a window AC without a window. If you are not a DIY enthusiast you may want to pay a handyman to do it for you.

4. Place the Window AC in a Sliding Door

Does your room have a sliding door? If it does, you are in luck. A sliding door is also one of the ways most folks use to vent a portable air conditioner in a room without a window.

Most sliding doors lead outside to a balcony or porch. That means that the air conditioner will release the hot air directly outside. Just open the sliding door and leave a gap the size of the AC unit.

Place the AC in the gap created then seal the space above the AC unit. There are sliding door sealing kits in the market but you can also use plexiglass sheets.

5. Other Alternatives

If you haven’t bought the window air conditioner yet, there are other better products in the market if the room you want to cool does not have a window.

To start with, you can consider a portable air conditioner. Although portable air conditioners need to be vented through the window, you can also vent them through the door, wall, dryer vent, ceiling or even chimney as a I wrote in this post.

Portable AC vented through wall

Another thing would be buying a swamp cooler instead. A swamp cooler, also known as an evaporative cooler uses water to cool a room through evaporation and do not need to be vented and have no condensate.

The only disadvantage of swamp coolers is that they are only ideal for arid areas. These are areas like the south Western States of Arizona and Nevada where relative humidity is quite low. These coolers will not work in humid states like Florida since they will increase the humidity making it even more uncomfortable to stay indoors.

Even with swamp coolers, you still need to open a door/window or even make a hole on the wall to bring in fresh dry air and allow humid air from the room to exit the room.

And basically that is everything about using a window air conditioners without a window. I hope that one of the methods discussed in this post will help you use your window AC in a room without a window.