Mold spores on my A/C filter

[wahoowad]

I try and replace the dust filter on my indoor air handler every two months. I think they recommend every month but I don't usually see enough dust on it when I check it every month. Every two months show some, not filthy, but that is when I change it. Sometimes I see small black spots that I assume are mold spores. I don't have a mold issue in this house and our region (Central VA) isn't known for mold issues in houses. Just curious if others see mold on their air filters. Maybe I went longer than 2 months this past time? It wasn't very dirty but I could see some dust on it. Humidity in my house has been low (55 - 60%) the last few months too.

 

[heat seeker]

I have an electrostatic filter for my AC, and have never had anything on it but dust. It doesn't get a whole lot of use, though, but it does get really humid up here in the summer.

Does dampness build up in the ductwork when the unit is not running? You could take a look after the unit has been off for a while.

If your air handler has a humidifier in it (for the heating season), maybe that needs to be shut off and drained for the summer. The water in it may be getting stagnant…just a thought. Is the condensate pump working properly? Maybe the water in its tray is funky and breeding mold spores.

Mold needs moisture to grow. Find your moisture source and eliminate it, and the mold should stop growing.