How to install window air conditioner horizontal sliding window

How to install window air conditioner horizontal sliding window


When the scorching summer heat arrives, a window air conditioner can be a lifesaver, providing cool and refreshing air within the comfort of your home. As the summer heat intensifies, installing a window air conditioner can be a practical and cost-effective solution to keep your living space comfortably cool. If you have a horizontal sliding window, don't worry! you can easily install a window air conditioner in a horizontal sliding window with the right technique. With a few simple steps and the right tools, you'll soon be enjoying the refreshing coolness of your new AC unit.

Materials and Tools Required:

Before starting the installation process, gather the following materials and tools:

  • Window air conditioner unit
  • Measuring tape
  • Plywood or Plexiglas (cut to fit the window opening)
  • Screwdriver or drill
  • Screws
  • Brackets (if necessary)
  • Weather stripping foam
  • Level
  • Support bracket (optional, if required by the manufacturer)
  • Safety goggles and gloves (for protection during installation)

Step-by-Step Guide to Installing a Window

Step 1: Measure the Window Opening:

Begin by measuring the width and height of your window opening to ensure the window air conditioner unit will fit properly. Take accurate measurements, as they will guide you in selecting the right-sized AC unit.

Step 2: Prepare the Window:

Clean the window frame and remove any obstructions. Ensure that the window slides smoothly and can support the weight of the air conditioner.

Step 3: Install the Support Bracket (if necessary):

Some air conditioner units require a support bracket for added stability. Consult the manufacturer's instructions to determine if your unit needs one. If required, follow the provided instructions to securely install the bracket.

Step 4: Cut the Plywood or Plexiglas:

To seal any gaps around the air conditioner, cut a piece of plywood or Plexiglas to the size of the window opening. This will help prevent drafts and increase energy efficiency. Make sure the material is sturdy enough to support the weight of the unit.

Step 5: Install the Weather Stripping Foam:

Apply weather stripping foam along the bottom edge of the window to create a seal and prevent air leakage. This will help maintain the cooling efficiency of the air conditioner.

Step 6: Place the Air Conditioner Unit:

Carefully lift the air conditioner unit and place it on the windowsill, centering it within the window opening. Ensure the unit is level using a spirit level. If needed, adjust the position of the unit by adding or removing shims beneath it.

Step 7: Secure the Air Conditioner Unit:

Depending on your specific unit, use the screws provided to attach the air conditioner to the window frame or the support bracket. Follow the manufacturer's instructions to ensure proper installation.

Step 8: Install the Plywood or Plexiglas:

Attach the cut plywood or Plexiglas to the window frame on the outside of the air conditioner unit. Secure it with screws, ensuring a snug fit. This step helps insulate the area around the air conditioner and prevents drafts.

Step 9: Test the Air Conditioner:

Before closing the window, turn on the air conditioner and ensure it is functioning correctly. Adjust the settings as desired to ensure cool air is blowing into the room.

Step 10: Seal Any Gaps:

Inspect the window area and seal any remaining gaps with weatherstripping or caulk to enhance energy efficiency and keep the cool air inside.


Installing a window air conditioner in a horizontal sliding window  doesn't have to be a daunting task that can significantly improve your indoor comfort during hot summer months. By following this step-by-step guide, you can ensure a secure installation and enjoy a refreshing and cool living space. Remember to carefully read and follow the manufacturer's instructions specific to your air conditioner

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