Before You Start
Proper installation is crucial for both performance and safety. A poorly installed window AC can fall, leak, or work inefficiently. This guide covers standard double-hung windows—the most common type for window AC installation.
Tools and Materials Needed
- Screwdriver (Phillips and flathead)
- Measuring tape
- Level
- Foam weather stripping
- L-brackets (usually included)
- Optional: Support bracket for heavy units
Step-by-Step Installation
1. Measure Your Window
Measure the window opening width and height. Most window ACs fit windows 23-36 inches wide, but check your unit's specifications.
2. Prepare the Unit
Attach the accordion panels to both sides of the AC if not pre-installed. These expand to fill gaps between the unit and window frame.
3. Position the Unit
With help, lift the AC into the window opening. The unit should tilt slightly backward (about 1/2 inch) to allow condensation drainage outside.
4. Lower the Window
Lower the window sash onto the top of the AC unit. It should rest snugly against the top mounting rail.
5. Secure the Unit
Install the L-brackets to secure the window sash to the frame, preventing the window from being opened. Extend accordion panels to fill side gaps and secure with screws.
6. Seal the Gaps
Apply foam weather stripping to any remaining gaps. This prevents hot air infiltration and improves efficiency.