Short answer: Mold grows in mini splits because the coil gets cold and wet when it cools, and dust that slips past the thin filters gives it something to grow on. It shows up as black spots on the vanes and dark lines on the blower wheel. Spraying it won’t remove it; the head needs to be opened up and the coil, blower wheel and drain pan cleaned.
Where mold hides in a mini split
- The blower wheel, the long squirrel cage behind the vanes. It sits right after the cold coil and usually has the most growth.
- The coil, behind the filters.
- The drain pan under the coil, where water sits.
- The vanes and the inside of the housing.
Why mini splits get moldy
Mini split filters are a thin mesh, so fine dust gets through and sticks to the wet coil and blower wheel. Add a dark space and moisture from cooling, and mold has everything it needs. Vermont summers are humid, so heads in bedrooms and basements tend to get the worst of it. A head that’s been oversized for its room can also short-cycle and stay damp.
How to check for mold
Turn the head off, lift the front cover and remove the filters. Shine a flashlight up through the vanes at the blower wheel. Black, fuzzy lines on the blades, or black spots on the vanes, mean mold or other growth. A musty smell when the unit starts is another sign.
Is mini split mold harmful?
How much risk mini split mold poses isn’t settled, and we won’t tell you it will make you sick. What we can say is that it’s growth you don’t want blowing into your room, some people are sensitive to mold, and it brings the smell and weaker airflow along with it. If anyone in your home has health concerns, talk to your doctor.
How mold is removed from a mini split
We open up each head and clean the coil, blower wheel, drain pan and housing with coil detergent and a rinse setup that catches the runoff. That removes the growth rather than covering it up. To slow it from coming back, keep the filters clean and have the heads cleaned once a year. With us, the first indoor head is $289, and the price per head goes down the more heads we clean in one visit.
Frequently asked questions
Are black spots in my mini split mold?
Usually. Black spots on the vanes or dark, fuzzy lines on the blower wheel are most often mold or other growth.
Can I spray my mini split to kill mold?
Sprays may help the smell for a while, but they don’t remove the growth from the blower wheel and coil. Avoid bleach and vinegar, which can damage the unit.
How do I keep mold from coming back?
Keep the filters clean, have the heads deep-cleaned once a year, and consider running the fan for a while after cooling so the coil can dry out.
Do you clean mold out of mini splits?
Yes. We open up each head and clean the coil, blower wheel, drain pan and housing with coil detergent and a contained rinse.
Related guides
- How often to clean a mini split
- Signs your mini split needs cleaning
- Why your mini split smells
- Cleaning a mini split yourself vs. hiring a pro
- How much mini split cleaning costs in Vermont
- Dryer vent cleaning
Sources
- Energy Vanguard: Ductless mini splits can get nasty inside
- Efficiency Vermont: How to clean and maintain your ductless heat pump system
- Trane: Why does my mini split smell?
Book a mini split deep clean
Mansfield Services cleans mini splits across Chittenden, Lamoille and Franklin counties. Book online in a couple of minutes, or call or text (802) 777-3210.
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