How to Repair an Air-Conditioning Vent

An air-conditioning vent allows the swift passage of conditioned air from the source into the location desired.

Unfortunately, there are times when these vents fail to do their job. A common, and costly, cause of this is because the vent is not properly insulated and is losing a significant amount of that conditioned air to elements surrounding the duct. A few steps will allow you to repair the vent and prevent leaks. .

Remove the register covering the vent. This usually can be done either with a screwdriver to remove the screws holding the register in place or by prying the plate from the vent.

Frame the walls, top and bottom around the vent's opening with masking tape. Keep the tape along the edge of the opening and not overlapping into it.

Rip off a piece of foam insulation stripping. Hold the piece along the length of the vent in the gap between the duct and the wall, top or bottom.

Push the insulation into the gap using the tip of a screwdriver. Don't force the insulation further than it will go.

Keep filling the gap with strips of insulation until it is flush with the duct and the edges around it.

Spread sealer over the insulation to cover it. Use a paintbrush to spread the sealer from the duct to the masking tape.

Allow the sealer to dry and peel off the masking tape. Replace the register over the vent.

Things You Will Need

  • Screwdriver
  • Masking tape
  • Foam insulation strips
  • Sealer
  • Paintbrush


  • Do not compress the insulation because foam insulation loses its properties once force is applied to it.

About the Author

Based in New York, Tim Burgone has been writing technology-related content since 1991. His work has appeared in “Wired” magazine and “Mac Addict” magazine. Burgone received the Frank L. Kern Literary Award in 2002. He holds a Bachelor of Fine Arts from St. John’s University in New York.