The exterior ductwork leading to the AC condenser is collecting water and beginning to rust. The obvious solution is to replace the duct work, but I am having problems finding someone to do that work. Is there another solution that I am not thinking of? I thought of creating some type of cover for that area but not sure if that would work. Looking for some creative solutions that could be done in a day or two.

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2 Answers 2


It's probably too late to preserve this duct. It looks like the metal is corroded to a substantial depth. Once the zinc coating (galvanization) is compromised it'll continue to rust. You could try a spray or brush-on coating, but you're unlikely to cover all vulnerable surfaces well enough to stop the inevitable.

This should be a simple connector duct with no mechanical hardware inside. I would replace it with aluminum or stainless, or simply replace it with new galvanized.

  • Disable the unit.
  • Remove the sheet metal screws.
  • Move the unit slightly to allow clearance, and lift out the plenum.
  • Temporarily cover the opening to stop pests.
  • Take it to an HVAC shop and ask them to reproduce it.
  • Reinstall.

Once you do that, and depending on what material you choose, it may make sense to construct a simple cover. It's difficult to keep things dry outside and near the ground, though, so I'm not sure it's worth the effort.


"Rust Converter." If you haven't rusted right through yet, that stuff converts rust to not-rust, and then you can get back to trying to keep the water from collecting there.

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