Las Vegas summers can be brutal, making a window air conditioner essential. However, installing one in a horizontal sliding window can seem challenging. Don’t worry! This guide will show you how to install your unit efficiently and safely, regardless of window type.

What You Will Find Out

  1. Prepping Your Window: Learn the necessary steps to prepare your window for installation.
  2. Step-by-Step Installation Guide: Follow detailed instructions for installing your air conditioner.
  3. Safety Tips: Discover essential safety precautions to ensure a secure setup.
  4. Maintenance and Troubleshooting: Keep your unit running efficiently with these tips.

Read on to make sure your process is as seamless as possible.

Know Your Sliding Window

First, it’s important to identify the type of window you have. Here’s a quick breakdown:

  • Horizontal Sliding Windows: These windows slide open left or right along a track.
  • Vertical Sliding Windows (Double-Hung): These windows have two sashes that slide up and down.

Safety First!

Window air conditioners can be heavy. Always check your window’s weight limit before installation. Exceeding this limit can damage the window frame and create a safety hazard. When lifting the unit, it’s wise to ask a helper to avoid strain or injury.

Preparing for Installation

Now that you understand your windows and safety precautions, let’s gather the tools and materials you’ll need:

  • Window air conditioner sized for your space (BTU)
  • Tape measure
  • Level
  • Screwdriver (Phillips head and flathead)
  • Drill (optional)
  • Utility knife
  • Pencil
  • Weather stripping or foam insulation
  • Standard AC unit bracket (optional)
  • Plywood board (cut to size, optional)
  • Plexiglass sheet (cut to size, optional for casement windows)

Installing The Air Conditioner

Step 1: Measure and Choose Your Method

  • Measure the exact width and height of your window opening. This will help you determine if your chosen cooling unit will fit properly.
  • Decide on your method. Here are your options:
    • Pre-made window AC bracket: These brackets are designed for specific window AC models and are relatively easy to install. Follow the manufacturer’s instructions for your specific bracket.
    • Building a wooden frame: This method is suitable for standard AC units that might not perfectly fit your window. We’ll provide a detailed guide in a later step.
    • Portable AC: If your windows aren’t compatible with traditional window AC, consider a portable unit. These units vent hot air through a hose and require no window modifications.

Step 2: Prepare Your Window

  • Open the window completely.
  • Remove the window screen.
  • Clean the window frame thoroughly. Dust and debris can hinder proper insulation.

Step 3: Install the Cooling Unit

For Pre-made Brackets:

  • Follow the specific instructions provided with your bracket. These typically involve attaching the brackets to the sides of the AC unit and then securing them to the window frame using screws.

For Building a Wooden Frame (Horizontal Sliding Windows):

  • Cut a piece of plywood to match the width of your window opening. The depth should be slightly less than the depth of your AC unit.
  • Attach 2×4 lumber pieces to the long sides of the plywood board to create a frame that will support the AC unit. Ensure the frame height allows for proper airflow above the unit.
  • Place the frame inside the window opening and use shims or leveling techniques to ensure it sits level and fits snugly.

For Vertical Sliding Windows:

  • Commercial brackets designed for casement windows might be suitable depending on your window and AC unit size.

Alternatively, consider a custom-built plexiglass sheet that can be cut to fit above the lower sash of your window. The AC unit would then rest on this plexiglass shelf.

Tip: Consulting a professional for proper measurements and plexiglass installation is recommended to ensure safety.

Step 4: Filling Gaps and Insulating

  • Use weather stripping or foam insulation** to fill any gaps between the cooling unit and the window frame. This will help improve cooling efficiency and prevent drafts.
  • For horizontally sliding windows: You can use masking tape to temporarily secure the AC unit and frame assembly in place before filling gaps on the sides and top.

Safety Considerations:

  • Weight distribution: Ensure the weight of the cooling unit is evenly distributed on the window frame to prevent damage.
     
  • Electrical safety: Always use a GFCI outlet and avoid overloading circuits.
  • Drainage: Proper condensate drainage is crucial to prevent water damage and mold growth. Most window air conditioning units have a drain spout that can be directed outside the window using a hose. Make sure the drainage hose is angled downward to allow for proper water flow.

 Tips and Troubleshooting

  • Maximize cooling efficiency: For optimal cooling, position the cooling unit so cool air can circulate freely throughout the room. Avoid placing furniture or curtains directly in front of the unit.
  • Uneven fit: If you encounter gaps between the window frame and the cooling unit, use additional weather stripping or foam insulation to fill them. In some cases, you might need to adjust the wooden frame to achieve a snug fit.
  • Leaks: Small leaks around the window unit can be addressed with additional weather stripping. For larger leaks, consult a professional to diagnose the source and ensure proper repair.

Maintaining Your Air Conditioner In a Sliding Window

  • Regularly clean the air filter to maintain optimal airflow and cooling efficiency.
  • Clean the exterior of the unit with a damp cloth to remove dust and debris.
  • At the end of the cooling season, properly drain any remaining condensate water and store the unit in a dry, protected location.

When to Call a Professional

While installing an air conditioner in a sliding window is achievable for many DIY enthusiasts, there are situations where seeking professional help is recommended:

  • Electrical Concerns: If you’re unsure about electrical safety or wiring procedures, it’s best to consult a licensed electrician.
  • Complex Window Types: For unique window styles or large, heavy units, a professional HVAC technician can ensure a safe and secure installation.
  • Leak Repairs: If you encounter significant leaks you cannot address with basic troubleshooting, call a professional to diagnose and fix the issue.

Benefits of Hiring a Professional


Here are some advantages of hiring a professional:

  • Peace of mind: Knowing your unit is installed correctly and safely offers peace of mind throughout the cooling season.
  • Efficiency: Professionals can ensure your AC is operating at peak efficiency, saving you money on energy bills.
  • Safety: They can identify and address any potential safety hazards related to electrical wiring or weight distribution.

Installing a Window Air Conditioner: Final Thoughts

By following these steps and considering the safety precautions, you can install a window air conditioner in your sliding window. For a smooth and worry-free experience, remember that Bob’s Repair is here to answer your questions and offer expert advice on all your Las Vegas air conditioning needs.