I shone a torch through the grille and the roller is grey and fuzzy – how long do I have?
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Popești-Leordeni, new block, 12,000 BTU Gree, 3 years old, bedroom. I took the filters out to wash them and shone a light behind: the fan roller has a grey fuzzy layer on every blade. It does not smell (or have I got used to it?). Should I stop it immediately or can I stretch another month until I have the money?
What is really happening
Dust is matte and shakes off; what is 'fuzzy' and stuck to the roller blades is mould mycelium, the living colony, producing spores and releasing them right into the air jet that reaches your bed. Studies on split units find the roller to be the most contaminated component, and at start-up the spore concentration in the room can rise tens of times. Smell habituation is real: olfactory receptors saturate under continuous exposure, which is why guests notice the smell and you do not. An extra month does not change the cost of sanitising, but it is 30 nights of exposure that were not necessary.
- A picture can document visible deposits.
- Colour and appearance do not reliably identify microorganisms.
- The appropriate assessment depends on the issue; a photo is not a laboratory test.
- The blower (cross-flow fan) is the most fungus-contaminated component of a split unit, more than the filter or the front of the evaporator. [Indoor Air, 2023]
- When a contaminated air conditioner starts, airborne fungal concentration in the room can jump from 40–920 to 5,500–100,000 CFU/m³. [Indoor Air, 2023]
- EPA advises not to run an HVAC system you know or suspect is mould-contaminated, because it spreads mould throughout the home. [US EPA, 2024]
- On filters of residential split units, Cladosporium (~32%), Aspergillus (~9%), Acremonium and Alternaria dominate – genera known as allergens. [Building and Environment, 2025]
What we do on site
- Collection bag under the unit, film over the bed.
- Cleaning solution on roller and evaporator, left to act to soften the mycelium.
- Pressure wash in place, roller turned blade by blade, evaporator both faces, pan.
- Sanitising solution on the clean surfaces.
- Outdoor unit, washed in place.
- Smell test with the window closed. See current rates on the Prices page.
What you can do yourself
- Until sanitising: sleep with the window ajar and the unit off, or use a fan.
- If you absolutely must run it, do so 15 minutes before entering the room, window open, then close it.
- Filters washed and dried – do not put them back wet.
What NOT to do
- Do not try to wipe the roller with cotton buds or a brush through the grille – you break the blades and scatter spores.
- Do not spray bathroom 'anti-mould' into the unit.
- Do not postpone 'until autumn'.
Prevention
The roller fouls first and worst; check it with a torch once a season. Annual sanitising and 'Fan' before shut-off.
When to call us
0764 012 943, Monday–Saturday 08:00–20:00. Popești-Leordeni – usually within 2–3 days.
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Read also
Sources (5)
- onlinelibrary.wiley.com/doi/10.1155/2023/8984619
- www.epa.gov/mold/brief-guide-mold-moisture-and-your-home
- www.epa.gov/mold/mold-remediation-schools-and-commercial-buildings-guide-chapter-3
- www.sciencedirect.com/science/article/abs/pii/S0360132325010303
- www.sciencedirect.com/science/article/abs/pii/S0048969719347333
The information on this page is educational and based on cited sources; it does not replace medical advice. We do not do repairs, installation or refrigerant circuit work.