How to Seal the AC to a Window

Many people use window air conditioning units to cool their homes during the hot summer months.

Seal your air conditioner to the window to keep cooling costs down.Seal your air conditioner to the window to keep cooling costs down.
Installing a window air conditioner without sealing the perimeter can allow cold air to escape, and hot air to get in. This leads to higher costs to keep your home comfortable. With a little bit of extra time and effort, you can seal your air conditioner to your window. This will save you money, and keep you cooler.

Hold a lighter or lit incense stick close to where the top of the air conditioner meets the window. If the flame flickers, or if the incense smoke is blown away, you have an air leak.

Go to your local hardware store and buy air conditioner foam seal.

Lift the window carefully and apply a strip of the foam to the underside of the window. Close the window tightly.

Hold a lighter or lit incense stick around the unit again to see if you have sealed all the gaps. If any gaps remain, apply the foam seal to those places.

Examine the air conditioner's accordion sashes to find any cracks or holes that may exist.

Cut small strips of duct tape to match the size of the cracks.

Apply the duct tape to the cracks. You may paint over the tape if you want it to blend with the unit.

Things You Will Need

  • Lighter
  • Air conditioner foam seal
  • Duct tape
  • Spray foam

Tip

  • For a more permanent solution, use spray foam instead of the foam seal.