How To Install AC In A Horizontal Sliding Window?

In our home, specifically the rooms, we frequently notice horizontal sliding windows. It is simple to install an air conditioner this way, but you must remember to gather your resources first and know what you should do. We researched from experts, and here is what we concluded.

Keep in mind these steps:

  • Check the width and length of your air conditioner.
  • Remove the window screen.
  • Trim the wood and put the frame together.
  • Assemble the frame.
  • Move the panel and open the window.
  • Plug in your unit.

Usually, sliding and double-hung windows are not compatible with window air conditioners. Installing your air conditioner just requires a few simple steps, enabling you to achieve your objective. Read on as we elaborate more on this topic.

Steps on installing ac in a horizontal sliding window, How To Install AC In A Horizontal Sliding Window?

Installing Your AC

Your sliding window may have a variety of air conditioners. Measure the window opening before purchasing your air conditioner so you will know how broad a unit you can attach. You can find detailed instructions for installing your air conditioner in a horizontal sliding window right here.

blank horizontal mock up poster hanging in shop window at night


You first need to measure the width of your air conditioner, taking into account any side outlets that protrude. Don't forget to calculate and estimate the height after that. The frame's height, excluding the top and bottom lips, must also be included in this measurement.

Window Screen And Frame

One side of the sliding window can be fully opened by sliding the frame. Remove any window screens that are used to block insects or dust. To fit your window air conditioner, you must leave the window entirely open.

Mosquito Net Frames Set for PVC Window Screens

Examine the windowsill too. The windowsill may be unable to sustain the unit's weight if it is old, frail, or damaged in any other way. Choose a different window or replace the windowsill.

Wood And Frame

Cut your lumber to the desired length and width first. Then use the measurements you take as a reference. Place a shorter two-by-four slab on the ground, then fasten the long slabs' tips to the smaller piece.

Consider the depth of the wood while using deck screws, using two at each connecting point. Place one short two-by-four between the long ones on the opposite end to create a rectangle. To begin with, make sure the edges are square.

Put The Frame Together

Rinse your air conditioner, and the bottom of the air conditioner should be against the exterior when it is placed in the frame. The upper lip is most likely U-shaped, with the back side being slightly short.

Overtop, place the last two-by-four piece. But hold off on tightening it yet. Adjust the air conditioner's tilt so that the upper lip's forward upright section properly lines up with the front corner of the wooden frame.

Install Your AC

To finish the installation, gently open the window and slide the interior panel to the opposite side of the window frame. If you want to add more stability, fasten it by inserting long screws through the piece of wood and into the framework surrounding the window hole.

Once it is flat with the side window jamb and rests against the support bracket, slide the air conditioner into the window opening. As the unit will be heavy, seek assistance.


Hand holding electric plug, Multiple socket with connected plugs

Lastly, plug in your device and ensure that it is operating properly. If your equipment isn't functioning correctly, check your installation to determine if there are any misaligned or loose parts, and make the necessary adjustments. Don't forget to seal any gaps in your frame so that the cool air from your air conditioner can circulate through them.

How Can You Support A Window Air Conditioner?

If you install window air conditioners correctly, they won't fall. Window air conditioners can be placed in an open window to provide a pleasant breeze, but the large units need to be supported for safety reasons. We investigated the ideal guidelines for you.

The steps in constructing a window air conditioner support are here:

  • Measure the window's width.
  • On the lumber, mark the channel's width.
  • Draw the channel depth on the four-inch face of the lumber
  • Attach the lumber to the window frame

People unaware of this additional support may risk falling out of the AC. To prevent the chilly winter wind from entering your flat, we will review how to seal the space between the window and the air conditioner. Read on as we go into greater detail about this subject.

Purchasing AC Brackets

The outdoor air conditioner unit on brackets and insulated copper tubes for its connection

Appliance retailers sell AC brackets, which you can purchase, but there is no assurance that a bracket will match your air conditioner's dimensions. Making homemade air conditioner support is more practical because you may modify the size and save money. Below is a list of instructions to do so in building AC support.

See this air conditioner bracket in Amazon.

Window's Width

Measure the depth and width of the channel in the window frame where the slides pass through after considering the window's width. Draw a pencil outline of the window's width on the lumber. Then, as indicated by the outline, cut the timber using the jigsaw to the window's width.

Width of the Channel

On the four-inch face of the wood, mark the channel's width. It must be completed on both ends, with the width at each end being marked with a pencil. You are more likely to leave a half-inch mark on both ends since a channel typically has half an inch width.

Channel's Depth

On the four-inch face of the timber, mark the top and bottom edges with a pencil to indicate the depth of the channel. Then, make marks on the top and bottom margins equal to half the channel depth. Lines drawn in this process should be parallel to those drawn in the previous step.

Attach The Lumber

Your air conditioner is ready to be installed through the window; just place the lumber on the lowest portion of the windowpane. If required, adjust the lumber, and it would be great if you positioned it exactly above the air conditioner. Ensure that the top lip of the air conditioner is pushing on the wood.

Can You Put An AC In Sideways?

air conditioner installed on window

Different-sized air conditioners are available; some are large enough to chill entire buildings, while others are compact devices for a single room. Even yet, some windows can be wider than some air conditioners, no matter how small. Will turning the air conditioner on its side be a quick fix for this?

An air conditioner cannot be used sideways because it is not intended to work that way. If turned sideways, components like condensate drains will stop working. The compressor is more critical since it will fail soon and could catch fire if it explodes due to insufficient or poor maintenance.

Because the compressor, fans, and other window AC components are not gravity-dependent, they should function just as well if you place the window air conditioner sideways on a window sill. Read on as we go into full depth about the reasons why it is not advisable.

air conditioner installed on rustic house window


The compressor receives vapor from the evaporator. The vapor must be reduced in size and made more compact by the compressor. The vapor is compressed and, as a result, leaves the compressor at a pressure and temperature that are significantly higher than when it left the evaporator.

Window air conditioners are made to stand upright. All of the internal supports were designed to assume that you will use a window air conditioner upright and in the proper position.


As a fan blows over the condenser, the refrigerant loses heat to the atmosphere. It condenses into a liquid because its pressure and temperature are higher than outside. You can temporarily run a window air conditioner sideways. The impact (length of time) of operating a window air conditioner sideways is uncertain.

Expansion Valve

The evaporator is just in front of the expansion valve. Its function is to lower the condensed refrigerant's pressure so that, when it enters the evaporator, the condensed refrigerant will boil as it absorbs heat from the air, converting it into vapor and starting the cycle all over again.

Overall, window air conditioners can still function even when positioned horizontally (if we don't obstruct any airflow). It is not advised to install a window air conditioner vertically.

In Closing

Steps on installing ac in a horizontal sliding window

You must learn six methods to install your air conditioner on horizontal sliding windows. Don't forget your supplies, like wood, screws, and similar items. Although installing this system is not difficult, you must be informed of the type of air conditioner you already have.

If you find this article informative, please check out these related articles:

Can You Use A Window AC With Central Air?

Where Is The Fuse In A Window Air Conditioner?

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