Why Is The Air Filter Wet?

August 20, 2015

While theair filter inside your central A/C should normally get dusty or dirty, a wet air filter is a sign of something worse. The filter media that traps airborne particulates isn't designed to function sopping wet and can't effectively filter air. In fact, a saturated filter may substantially block airflow through the system, not only reducing comfort in the house, but also stressing A/C components like the blower motor and compressor. So where's the wetness coming from?

Why It's Wet Gallons of water vapor removed from the air by the indoor evaporator coil dribbles down into a condensate drip pan, where it's diverted into a line connected to your household drain system. In an air handler with a standard up-flow design, the air filter is located close to the condensate drain system and just below it. If the condensate drain becomes obstructed, the drip pan quickly overflows and water runs down into the air filter.

How a Professional Handles It A qualified HVAC service technician can troubleshoot the obstructed condensate drain pan and drain line. Sometimes, the clog is caused by some loose-fill insulation that has found its way into the drain pan. More often, however, it's a result of algae or mold growth in the warm, wet environment of the pan or drain line. The technician can clear the blockage, then sterilize the pan and drain line. To prevent recurrence of algae growth, time-release biocide cartridges can be installed to continuously inhibit algae or mold for the length of the entire cooling season.

What You Can Do If you haven't had condensate drain problems, you can help prevent them and avoid a wet air filter by pouring a cup of household bleach into the condensate drain pan once a month during cooling season. This will kill incipient mold and algae and head off potential drain blockages. For more information about professional service to resolve a wet air filter in Des Moines, contact Lozier Heating & Cooling. Our goal is to help educate our customers in the greater Des Moines, Iowa area about energy and home comfort issues (specific to HVAC systems). Credit/Copyright Attribution: "Matt Howard/Shutterstock"