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Solving Common Condensate Drain Problems

Many homeowners don’t realize that their central air conditioning system not only cools the home by removing heat energy; it also removes moisture from the air. That moisture has to go someplace, and if all is working correctly, that “someplace” is a condensate pan underneath the evaporator coil. A condensate drain line then removes the moisture from the house.

Over time, however, the condensate drain can get clogged or otherwise malfunction, allowing the water to back up and spill into your home, potentially damaging floors, walls, fixtures, furniture and other belongings.

Regular preventative maintenance on your air conditioning system usually is all that’s required to keep your condensate drain from malfunctioning. Plus you, the homeowner, can inspect the drain periodically to make sure there’s no backup or other problem.

Following are some common condensate drain problems:


The damp area around the condensate pan and drain is a welcoming environment for algae as well as a magnet for dust and debris. These materials can accumulate and block the drain, leading to the aforementioned overflow and flooding. This often does substantial damage long before the homeowner realizes there’s a problem.

Drain trap problems

Central A/C systems typically route the condensate from the cooling process through a U-shaped trap built into the drain line. This keeps gasses and sewer fumes from backing up through the drain back into the house near the evaporator coil. If you smell a bad odor coming from the A/C supply registers, this could mean a malfunctioning drain trap. This problem should be addressed immediately.

Mold and mildew growth

The area around the condensate pan is a perfect breeding ground for mold and mildew. When this happens, it can infiltrate household air while the air conditioning is operating or, if mold settles on the evaporator coil, it can restrict the heat exchange that’s vital to effective air conditioning.

Please contact us at Beyer Boys for a comprehensive maintenance check on the cooling system in your San Antonio area home. We will take steps to prevent problems with the condensate drain and other issues with your central A/C.

Our goal is to help educate our customers in the greater San Antonio, Texas area about energy and home comfort issues (specific to HVAC systems).