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Wet Air Filter? One Of These Causes May Be To Blame

Your furnace or A/C air filter is a fiber mesh that can catch and hold particulate pollution in the air. Unfortunately, the same mesh that catches dust and pollen can also catch and hold water. When that happens, you may be breeding mold and mildew spores in the very thing meant to strain them out of your circulating air. A wet air filter can be caused by a number of issues.

Old Air Filter

As your air filter catches dust and other debris, it will slowly begin to clog. Technically, this makes the filter more efficient at catching particles. As the holes in the mesh fill up, it’s harder for anything to get through. But in addition to making it harder for your fan to pull air into your system, this also makes it easier for water to be caught and held in the filter mesh.

A/C Isn’t Draining

Your air conditioner forces a bit of humidity out of your indoor air as it runs. If the condensation isn’t draining, it may pool inside your A/C or find its way to your air filter. A/C maintenance can help prevent this, as can rinsing out your drain with a dilute bleach solution.

Poorly Installed A/C

Your A/C isn’t sized correctly, or wasn’t properly installed. If your A/C wasn’t correctly installed, or you’ve made a number of efficiency upgrades to your home, you may have issues. In particular, if your A/C is overpowered for the amount of cooling your home needs, it may overcool your home before shutting off to bring your home back to its proper temperature. That can lead to condensation issues, as well as system strain.


Your home has overall humidity issues. If your indoor air is humid, moisture can be drawn into the filter mesh where it won’t evaporate, because the air around it is already saturated. Consider a whole-house dehumidifier, if you struggle with high humidity in your home.

If you’ve got a wet air filter in your Phoenix home, call us up at Wolff Mechanical to learn more.

Our goal is to help educate our customers in the Phoenix Valley area of Arizona about energy and home comfort issues (specific to HVAC systems).

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