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5 Surprising Ways That Air Conditioning Ducts Get Damaged

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When it comes to a functioning air conditioning system, the duct work is just as important as the condensing unit that actually cools and dehumidifies the air. When your ducts are badly damaged, the air flow decreases until you notice the lack of cooling power or the reduced air movement from your vents. Check for signs of these five unusual ways that ducts can end up damaged.


Rising water or a leaking pipe can make a mess of your floors, but flooding in the home can also damage your duct work if it's installed under the floor or the water comes from the air conditioner itself. Exposure to all the water left behind by a flood causes the following:

  • Rusting, which eventually leaves holes in the duct for air to escape through
  • Mold and mildew growth, which requires cleaning that could damage the ducts
  • Seam separation and collapse, if there's enough water to weigh down the ducts and pull them apart.

Even a very small and slow leak from a pipe or drain could result in a rusted duct that lets a large percentage of your cold air escape into a wall or ceiling cavity instead of reaching its destination.


It's all too easy for a homeowner or professional repair technician to accidentally crush a section of duct work while working on another part of the home. Sometimes duct sections are even crushed during the initial installation, and no amount of trying to hammer out the dents will allow a crumpled section to fit tightly with the rest of the system again. Flexible ducts are particularly easy to crush with a hand or foot, but even the old-fashioned and boxy rigid metal ducts can become so dented that air flow is greatly diminished.


Getting your ducts cleaned is a good way to control the amount of dust and mildew flying around your house, but only if you have it done regularly enough that there's just a thin layer of material to remove each time. When a cleaning team has to scrub and scour the ducts to remove all the contaminants, there's a greater chance for serious damage to the interior wall. Duct cleaning brushes can rip off the vinyl or plastic linings inside flexible duct or knock a hole through a weakened sheet metal section that had been rusting for a few years.


This is a particularly rare cause of duct problems, but it does happen. Sometimes lined duct work is manufactured without part of the lining in place, most likely due to an equipment malfunction that misaligned materials as they were pressed together. This results in exposed insulation that gathers more dust and serves as a better breeding ground for mold if moisture is introduced. If an air conditioning repair technician discovers missing lining during an inspection, it's not too hard to replace the most accessible sections and use a spray sealant product to protect the exposed insulation where it's harder to access the ducts.


Finally, don't forget about how destructive rats, mice, and squirrels can be when they decide to turn your duct work into their new homes. It only takes one family of rodents to create a serious odor problem in addition to the holes they'll chew through the ducts to let your cold air go to waste. You can set the usual spring traps inside the ducts to catch rodents or call in a pest control company, but make sure the air conditioning system stays off until the rodents are gone and you've had the system professionally cleaned. Using the air conditioner with rodents or their residue in the ducts can spread dangerous bacteria.

If you find your ducts are damaged or otherwise not working, contact a professional air conditioning repair company to assist you.