What causes the black mildew on air conditioning vents and on the adjacent
ceiling? Why do only some of the vents in my newly-built house get this
while others don't?
What's the best way to get rid of the mildew and to prevent it from
If it is a newly built home, I suggest you go back to the builder and
have them address the issue.
Mold will grow just about anywhere it is damp. A/C dries the air, but
it can cause condensation on the vent pipes is they pass though an area that
is moist enough.
The problem with trying to solve your problem from here is we have no
way of seeing exactly what is going on. Any good tech should be able to
walk in and in a minute to two identify the cause and offer a solution.
Most of the time it is from the vent being improperly insulated. In other
words, there is bare metal exposed to excessive heat in the attic space.
When cold air hits the hot metal, condensation is the result. The area
around the vent(s) needs to be insulated. If you are still "under warranty"
with the builder, I would contact hi, and explain your problem.
I wouldn't clean it until the builder sees it. After that, and, if it's not
too bad, a simple bathroom cleaner (mildew remover) can be used.
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