Start with humidity
Indoor relative humidity should sit around 40–60%; the EPA recommends keeping it below 60% to limit mold. In South Florida it's easy for a house to sit at 65–70% even with the AC running, and that is where musty smells, mold on supply vents and the cold-but-clammy feeling come from.
The usual causes are an oversized AC that shuts off before it dehumidifies, a fan set to On instead of Auto (which re-evaporates water off the coil back into the house), leaky return ducts pulling humid attic air in, or a drain problem. We check those first, because they're often cheaper to fix than adding equipment.
When equipment helps
- Whole-home dehumidifier: for tight, well-insulated homes, homes where the AC is correctly sized but the latent load is high, or when you're away and the house sits closed.
- Better filtration: a higher-MERV media filter, sized so it doesn't choke the blower. A filter that's too restrictive can freeze the coil.
- UV light at the coil: limits growth on the coil and in the drain pan, which helps keep drains flowing.
- Variable-speed equipment at replacement time: longer, slower cycles remove far more moisture.
We don't sell ionizers or ozone generators. Ozone is a lung irritant, and the EPA advises against ozone generators in occupied spaces.
Mold on vents or in the air handler
Small spots on a supply vent usually mean the register is colder than the dew point of the room, which is a humidity and airflow problem. Growth inside the air handler or ductwork needs cleaning and the moisture source fixed, or it comes back. Large areas of mold may need a licensed mold assessor under Florida law; we'll tell you if we think that's the case.
Where we do this
Indoor Air Quality & Humidity across Miami-Dade, Broward and Palm Beach counties. Local notes (housing stock, permits, common problems) for each city:
AventuraSunny Isles BeachNorth Miami BeachHallandale BeachHollywoodNorth MiamiMiami GardensMiramarPembroke PinesHialeahDavieMiami BeachFort LauderdalePlantationMiamiDoralSunriseCoral GablesWestonPompano BeachKendallPinecrestCoral SpringsDeerfield BeachBoca RatonDelray BeachBoynton BeachWest Palm Beach