How to Seal an Air Conditioner Window Gap

If there is a gap between an air conditioner and the frame of the window in which it is installed, cool air will leak inside during the winter and warm air in the summer. Also, when the air conditioner blows out cold air, some of it it will escape outside through the gap, never allowing the room to properly cool. Even though units normally have accordion-style extensions on each side, cover up any areas that the extensions leave open, and avoid costly energy loss.

Things You'll Need

• Ruler/tape measure
• Adhesive-type air conditioner foam seal
• Utility knife

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Instructions

1. • 1

     Measure the length of the gap between the air conditioner unit and the window, or the gap between the window sashes, using a ruler or a tape measure.

   • 2

     Cut a strip of adhesive-type, air conditioner foam seal to the correct length, using a utility knife.

   • 3

     Press the foam seal into place within the gap, by hand, so that the gap is completely sealed.