There are a couple of steps you can take to fix a hole in an air conditioning flex duct, including using mastic caulk. To use this material, apply it onto the exposed duct, and use a caulking gun to fill in the hole. Allow the mastic to dry for 24 to 48 hours, and then remove the mastic and wax paper backing.
First, measure the length, width, and height of the hole. Next, cut a sheet metal patch to fit over the hole, overlapping it by a few inches. Drive self-tapping sheet metal screws into each corner to secure the patch. If the duct is made of fiberboard, wrap it with foil tape. Apply silicone caulk to prevent air leaks, and then reattach the duct.
Next, determine the size of the hole in the air duct. You should make sure that you cut the duct at the correct size, and that the duct has a strong enough base. Using the measurements, you can decide whether or not you’d like to replace the entire ducted system or just the damaged portion. Afterward, you’ll need to know the sized and location of the duct to ensure that it’s installed properly.
If you are in the East Valley area including Gilbert, Mesa, Tempe, Chandler, and surrounding areas and need help repairing your Air Conditioner contact Dukes of Air for help.