A/C Fan On or Auto to Prevent Mold?

Set a/c fan to auto in south Florida.Aaaah, autumn in Florida. The temperature is down to 90ºF and just a bit less humid…And the snowbirds are starting to fly south. This week alone customers called from Ohio, New York and New Jersey with the same mold problem: the house watch person checked the condo and found the a/c is running but there’s mold on all the furniture! It was fine when they left last March. What happened?!? How can I prevent mold in my vacation home?

And the culprit is...

All three times the culprit was the incorrect air conditioner fan setting. Such a simple little setting can cause a big problem!  So here’s the skinny: make sure you’re a/c fan is set to “Auto.” The “auto” setting allows the thermostat to turn on the a/c when it reaches the set temperature. So, if your thermostat is set to 77ºF, when the inside air temperature reaches 77ºF the a/c will kick on, cool the house and pull moisture out of the air. The moisture is funneled out of the house via the drain line. The Auto setting also uses less energy because the fan only runs during the heating or cooling cycle.

If the fan is set the “on” position, the fan runs constantly. Up north that may work, circulating warm dry air. But in south Florida, it circulates warm moist air, which can spawn mold growth. When the temperature reaches 77ºF, the a/c will still kick on and cool and reduce the humidity. But until it does, the fan is blowing humid air throughout the house. We’ve also noticed that the moving air holds a temperature longer, even though its higher in humidity, so cooling/drying cycle rarely kicks on. (This is when people start to notice a “stuffy” smell in the house.) The constant air movement can clog the air filter faster, making the air handler work harder when it does cool. If you’re not home for months at a time, you might notice a spike in your FPL bill b/c the fan is running constantly.

the Real mold guy says...

In south Florida, we recommend using the Auto setting and leaving a ceiling fan or two running on low. We’ve found this combination provides the best air flow and humidity control to prevent mold in your Florida home.

For questions or to schedule your 32-point mold prevention inspection and SummerizationTM call us at 561-693-8955 or email Amy@RealMoldGuy.com

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