Best Sliding Window Air Conditioners

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There are few things as unbearable as a hot room when you want to sleep or relax. Did you know that one way to make life easier is to use a sliding window air conditioner? 

These casement AC units are much cheaper than an central AC system and great for windows that close and open from side to side.

We’ve picked out the Frigidaire FFRS1022R1 Slider/Casement Window Air Conditioner as the top model of rather than trawling your way through the options.

Our Picks for Best Sliding Window Air Conditioners

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Sliding Window Air Conditioners Reviews

1. Frigidaire 10,000BTU Slider/Casement Window Air Conditioner— Best Overall 

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This unit is an AC for side sliding windows and casement and has a high energy efficiency ratio, which lowers the operating costs. It’s our top pick for its effectiveness in a large room and dehumidifier function.

You can effectively lower the temperature of a 450 square-foot room with this model. On top of this, the antibacterial dehumidifier mode removes up to 3.4 pints of water per hour, which is great for reducing allergies and avoiding mold. 

It also comes with a remote, and you can track the temperature on the LED screen. This allows for optimum hands-off temperature control via the four fan speeds.

The only downside is that, it’s too heavy to install alone. It’s also slightly loud. 


  • Dehumidification.
  • Antibacterial filtration system.
  • 450 square-foot coverage.
  • Four fan speeds.


  • You need a minimum of 21½ inches of window height.
  • Needs another pair of hands for installation.

2. LG Energy Star Window Wi-Fi Air Conditioner— Runner up

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The LG Energy Star comes with a slide in-out chassis, making installation easy. Once installed, you can begin using it immediately. Connect it to your Wi-Fi and control the unit even when you aren’t home through the ThinQ app. 

They offer a few different versions. The 10,000BTUs unit will cool a large room up to 450 square feet, which is the industry standard. Also, choose from three cooling speed fans, which helps airflow customization, especially when paired with the four-way air deflection system.

You can also select the energy-saving mode, which is a great feature to help the environment. Although, with an energy efficiency rating (EER) of 12.1, it’s quite eco-friendly already. It’s also one of the quieter models. Despite this, some customers do mention that it’s noisy. 

If your window is smaller than 19¾” wide and 12¾” high, you’ll have a problem fitting this in it. But, the features add up to give it a boost over the competition, making it one of our top-rated options.


  • Energy Star compliant.
  • Easy-clean mesh filter.
  • SmartThinQ app for Wi-Fi control.
  • Dehumidifier function.


  • Some may find it noisy.
  • Limited to a window that’s 19¾” wide and 12¾” high.

3. Soleus Air Exclusive Energy Star Window Air Conditioner – Best for Vertical Sliding Windows

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This modern slider window AC is perfect for both vertical and horizontal sliding windows. One of the best features is that it keeps your window view as it will not take much space in your window.

It is also very easy to install it thanks to its unique design – you can simply put it on the window sill without worrying about it will fall. The remote ensures you can handle it when sitting on your cozy sofa and it is quiet enough for you to take a good snap.

Plus, this sliding window ac unit is smart which can choose the most energy-efficient mode for you according to the room temperature. We like its unique design and we recommend you take a look at it if you are not on a budget.


  • Space-saving design.
  • Quiet operation.
  • Automatic model.
  • Remote control included.


  • A bit expensive.

4. hOmeLabs 5,000BTU Window Air Conditioner—Most User-Friendly

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This air conditioner unit is small but still powerful and, with its mechanical controls, is easy to use. Choose from seven cooling settings and a fan setting—high or low.

With a 5,000BTUs output—the lowest on this list—this unit will cool an average-sized room of 150 square feet but will struggle in bigger rooms. It’s great for a bedroom or an RV and comes with a mounting kit, making it easy to install.

It also has a washable mesh filter, which catches air contaminants and helps prevent allergies and respiratory problems. Check the filter regularly, as there’s no LED indicator to let you know when it needs cleaning. 

Finally, its EER rating is 11, making it energy-efficient, and it is not noisy.


  • Seven fan speeds.
  • Mounting kit included.
  • Compact.
  • Easy to operate.


  • Not strong enough for very large rooms.
  • No cleaning indicator.

5. PerfectAire 10,000BTU Slider/Casement Air Conditioner—Best for Casement (Crank-Out) 

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This horizontal window air conditioner is versatile as it works with both crank-out casement windows and horizontal sliding windows. The EER is 10.4, which is lower than some but still decent. 

Installation is easy as it comes with a mounting kit. Once installed, this 10,000BTUs unit will comfortably cool a 450 square-foot room, which is right in the zone as per Energy Star suggestions, and you can adjust the temperature from 62 to 86 degrees Fahrenheit.

Also, the filter is easy to remove and washable, while an LED activates when the filter needs cleaning. 

It’s a little louder than the competition, being right on the cusp of the acceptable noise level at 58dB on medium. Even still, it shouldn’t be too disturbing, but there are quieter options.


  • 450 square-foot coverage.
  • Mounting kit included.
  • Easy-clean filter.
  • Easily adjustable temperature settings.


  • Louder than average and may not create white noise.
  • Sub-par EER rating.

6. Koldfront 8,000BTU Casement Air Conditioner with Dehumidifier -Best for Horizontal Sliding Window

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This horizontal Koldfront unit is Energy Star approved and has an EER rating of 11.0, so expect the operating costs to be low. Another plus is that it’s quieter than some others, with a sound rating of 49dB

It has several modes to choose from, so it’s quite on-par with the competition:

  • Dry.
  • Dehumidification. 
  • Sleep.
  • Energy saver. 
  • Cool. 

On top of the modes, you can also choose from four different airspeeds—auto, high, medium, and low. This allows you to get the right kind of breeze, no matter how hot it is.

Note that this 8,000BTUs unit has a washable filter and will cool a large room up to 350 square feet quickly, which is good for its power capacity. You can also operate it with the remote from a comfortable 16 feet.

But, be aware that some customers report that it doesn’t cool their rooms effectively. But, we wonder if they have the right BTU to square foot ratio.  This is AC unit is not for vertical sliding windows.


  • 16-foot remote range.
  • Digital display.
  • Dehumidification and sleep mode.
  • Includes installation kit.


  • No timer included.
  • Customers report it doesn’t cool rooms effectively.

7. TCL 5WR1-A 5,000BTU Window Air Conditioner—Best Value

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You’ll love using this minimalist unit as, at 50dB, it’s fairly quiet when you’re sleeping. It’s also operated with rotary controls, which some may find less convenient, but it saves on remote batteries and eliminates the need for fancy electronics. This reduces the cost significantly and also contributes to its EER of 11.0

You can choose from two cooling and two fan speeds for this 5,000BTU unit to effectively cool a 150 square-foot room, which is less power than others on this list. If you want to cool a large room, it may not be sufficient. Having said this, at the price, it’s a steal if you only need cooling in a smaller space. 

It will also fit most sliding windows and includes a mounting bracket, so setup is quick.

On top of this, the reusable filter helps reduce room odors and bacteria, and users particularly like that the unit will auto-restart should the power go out. 


  • Programmable timer.
  • 50dB noise level.
  • 150 square-foot coverage.
  • Washable and reusable filter.


  • Doesn’t come with a remote.
  • Not suitable for large rooms.

What to Look for in the Best Sliding Window Air Conditioners 

When narrowing down the best sliding window ac units, consider the following factors:

Cooling Power 

When choosing an air conditioner’s cooling power, take into consideration:

  • Room size.
  • Number of people in the room.
  • How much sunlight the room gets.

For an air conditioner to be effective, it should have a minimum of 20BTUs for 1 square foot.

It’s best to follow the Energy Star recommendations, though. They suggest a cooling capacity of 5,000BTUs for rooms between 100 and 150 square feet. A 350 square-foot room needs an 8,000BTUs capacity.

You do need to tweak the required cooling power, based on the room’s sunlight:

  • No sunlight: Reduce the required cooling capacity by 10 percent.
  • Sunlight for most of the day: Increase the required capacity by 10 percent. 


Although these air conditioners may be compact, you still need to measure the sliding window’s width and height.

When doing this, make sure that you’ve pushed the window as far as it will go before you take the measurements. 

Also, if you get an air conditioner that has 8,000+ BTUs, you’d need someone to help you with the installation, as it will be heavy.

Vertical or Horizontal 

Most small air conditioning units are designed for vertical sliding windows, and they’re also easier to install. They’re named after the way the window opens, and not their shape, so you’ll find that some models can work in both types of windows. 

A vertical sliding window AC unit rests in place and doesn’t require much structural support. They also come in various shapes and sizes, allowing you to get the right fit for the window. 

Horizontal sliding window air conditioners tend to be thinner and taller than the traditional air conditioning unit.

It’s important to note that there’s no standard casement size for both horizontal and vertical air conditioners, so you’d have to take the window measurements before buying. 

Noise Level

If you wish to install a sideways sliding window air conditioner in the bedroom, make sure you get a quiet one. Before bringing your new air conditioner home, check the decibel rating, as the quietest air conditioners have a rating of 40dB to 60dB.

The industry considers anything above 60dB to be “noisy.”


There’s real value in having an air conditioner that filters dust and contaminants that could cause health issues.

Some of the best sliding window air conditioners can dehumidify the room, which means to remove the moisture from the air, helping to: 

  • Prevent mold. 
  • Eliminate dust mites.
  • Improve air quality.

When looking at sliding window air conditioners, you also have a choice of two filters:

Removable/Washable Air Filters 

Some air conditioners have reusable filters that you can take out and wash. This is helpful as it saves you money because you don’t have to replace the filter.

These can last anywhere from a few months to a year, depending on various factors, such as how often you use your AC, if you have pets and if you live in a dusty area. 

Replaceable Filters 

Other air conditioners will require you to replace the filter, but this hinges on whether you have pets:

  • No pets: Replace every 90 days.
  • Pets: Replace every 60 days.

Even so, this still varies based on usage and make of the air conditioner. 

Replaceable filters are more expensive than the washable counterparts, and you may not be able to install a new one yourself, depending on the unit’s complexity.


How Do I Install a Sliding Window Air Conditioner? 

You can install a sliding window air conditioner using these steps:

  1. Fully open your window. 
  2. Put the unit on the bottom of the window, making sure the grooves underneath hold it in place.
  3. Move the window so it touches the unit.
  4. Attach the installation window to seal the entire window. 
  5. Once sealed, plug it into the outlet and switch it on. 
Easy way to install window ac unit

Why Is a Sliding Window Air Conditioner Better Than Others? 

A sliding window air conditioner is better than others mainly because you can use it with both horizontal sliding windows and casements. When winter comes, you can remove it and store it until needed. This also means no draughts, as you can close the window completely. 

Are There Any Negatives to Choosing a Sliding Window Air Conditioner? 

The main negative of a sliding window air conditioner is that a trespasser could remove the air conditioning unit from the window, which would leave the house open to anyone. To stop this from happening, lock the window or install an alarm.  If this is an issue for you, you could consider a ductless mini split AC.


We recommend the Frigidaire Slider Window Air Conditioner. It’s our best overall option for side sliding windows. It is designed for casements and sliding windows and is powerful enough to keep you and your partner cool in summer or in a large room. 

Our runner-up is the No products found.. The combination of Wi-Fi technology, good cooling capacity, and dehumidifying function will keep you and your loved ones cool and healthy while you control it from anywhere.

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Welcome to Air Wisely! I am Darren. I worked as a plumber for years and found that my clients were interested in learning basic HVAC knowledge. That's why I build this site.