Mold in the closets, a musty smell every time the mini-split starts, allergies that flare on vog days: these are HVAC problems, and they are fixable.
Humidity is the root cause
Hawaii indoor humidity often sits at 65 to 75 percent. Mold grows above 60. An air conditioner removes moisture only while it runs; an oversized unit that short-cycles removes very little. Step one is measuring humidity with a cheap hygrometer. If it is above 60 percent with the AC running, the system is not doing its job.
Fixes, in order of impact
- Correct sizing and longer run times. Sometimes a fan-speed or thermostat adjustment helps; sometimes it means right-sizing at replacement.
- Whole-home dehumidifier. Ducted or standalone units hold the house at 50 percent regardless of how much the AC runs. See indoor air quality and dehumidification.
- Clean the coil and blower. Mini-split heads grow mold on the blower wheel; a deep clean removes the smell and restores airflow. Part of mini-split service.
- Seal duct leaks. Leaky returns pull humid attic air into the system. Our duct sealing fixes that.
- UV coil light. Keeps the coil surface from growing biofilm between cleanings.
Vog on the Big Island
Sulfur dioxide and fine particulate from Kilauea drift into Kona, Ocean View, Pahala and sometimes Hilo. Indoors, a MERV-13 filter or a HEPA bypass filter captures particulate, and running the system in recirculate keeps outside air out on heavy days. Filters load faster in vog season; change them monthly.
Ask about air quality upgrades during any maintenance visit, or see local pages for Kailua-Kona, Hilo, Honolulu and Kapaa.