How Do I Know If My AC Unit Is Spreading Mold?

A musty odor when the AC runs is often the first clue. Mold grows in damp, dark places like the drain pan, coils, or filter. If you smell it, you likely have a mold problem. The smell can be strongest when you first turn the unit on after it has been off for a while.

Visible dark spots on the vents, grille, or filter are another sign. Check these areas with a flashlight. Look for speckles or patches that are black, green, or brown. Also, pay attention to your own health. Sneezing, coughing, or watery eyes when the AC is on can point to mold spores in the air. These symptoms may fade when you leave the room or go outside.

Turn off the AC and open windows to air out the room. Remove the filter and wash it with warm water and mild soap. Let it dry fully before putting it back. While the filter is out, take a look at the area behind it. If you see heavy mold growth there, you may need to call the pros.

Check the drain pan for standing water. If you see water, sponge it up. Wipe down visible mold with a damp cloth and a little detergent. Do not use bleach on all surfaces, as it can damage some materials. Wear gloves and a mask to avoid breathing in spores while you work.

• Inspect the air filter monthly
• Keep the area around the unit clear
• Wipe up any water spills quickly
• Check the drain line for blockages
• Run the fan-only mode to dry out the unit

Keep the filter clean and replace it when it looks dirty. Run the fan for a few minutes after cooling to dry the coils. This simple step cuts down on moisture. You can also schedule a quick visual check of the unit at the start of each cooling season to catch problems early.

Make sure the drain line stays clear. If you live in Cincinnati, note where the drain exits so you can check it now and then. Also, keep the area around the unit clear of dust and clutter.