How to Install a Window Air Conditioner - Step by Step

On February 16, 2025 By newsroom Topic: Appliance Buyers Guide

Installing a window air conditioner properly is crucial for optimal performance and safety. Follow these seven steps for a secure and efficient setup.


1. Read the Instructions

  • Always start by reviewing the manufacturer’s installation guide for specific requirements.
  • Each model may have unique steps, especially U-shaped designs.

2. Test the Unit First

  • Remove all packaging materials like foam blocks, tape, and fasteners.
  • Plug in and test the AC before installation to ensure it works.

Pro Tip: Handle the backside carefully—it has thin, sharp cooling fins that can cause cuts.


3. Attach the Side Panels

  • Attach the accordion-style side extensions to close gaps once the unit is in the window.
  • If included, install the top metal rail for added stability.

4. Position the AC in the Window

  • Raise the window sash and center the AC on the windowsill (front-to-back and left-to-right).
  • Hold the unit securely as most of its weight will hang outside.
  • Lower the window sash onto the metal rail behind the AC.
  • For upper-floor apartments, consider using a support bracket ($30–$100).

5. Ensure Proper Drainage

  • Check the unit's drainage system:
  • For slanted drain pans, keep the AC level.
  • For other models, ensure the unit slopes slightly outward to direct water away from your home.
  • Use a level or place a ball on top of the AC—it should roll gently outward.

6. Secure the Unit

  • Install the sash lock or L-bracket to prevent the window from opening.
  • Alternative: Use a wooden dowel or curtain rod for vinyl windows to avoid drilling holes.

7. Seal All Gaps

  • Extend the accordion panels fully to seal the sides of the AC.
  • Use the foam weather stripping to fill gaps at the top and between window panes.
  • Attach insulating foam panels (if provided) to minimize air leaks and noise.

Bonus Tips for Efficiency

  • Choose the right AC size for your room for maximum cooling efficiency.

By following these steps, you can safely install your window AC and enjoy a cooler, quieter, and more comfortable space all summer long.


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