I bought an ozone generator for the AC smell – fine for two days, then back to square one
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Hi. Berceni, Ciceu alley, 1970s block, 9,000 BTU Gree, 6 years old. For two days it smelled 'clean', then the mould smell came back identical. Did I waste the money? What should I have done? See current rates on the Prices page.
What is really happening
The smell is the product of the biofilm, not the biofilm itself. Ozone, like any gaseous oxidant, reacts with odour molecules in the air and with the top layer of the biofilm, but it does not penetrate its thickness or detach it from the aluminium; the factory stays intact and restocks within two days. On top of that, ozone irritates the airways at any concentration where it would have an effect. The principle in all remediation guidance: biological material is physically removed; agents that 'kill' leave behind spores and allergenic fragments, which are resuspended anyway once the fan starts.
- Deposits or moisture inside the unit.
- The condensate drainage route.
- Sources within the room, assessed separately.
- EPA principle: mould must be physically removed, not merely 'killed'; biocides are not recommended as routine practice. [US EPA, 2024]
- Mould remains allergenic even when dead, so merely 'killing' it with a spray does not solve the problem – it must be physically removed. [US EPA, 2024]
- Spores deposited in air systems resuspend when the fan starts, which is why cleaning must remove them, not just inactivate them. [Science of The Total Environment, 2019]
- Antifungal agents tested in the laboratory show variable efficacy against indoor air fungi, and many do not remove already-deposited spores. [International Journal of Environmental R, 2015]
What we do on site
- Inspection with you present; ozone usually bleaches the surface layer slightly, but underneath it is unchanged.
- Collection bag, cleaning solution, pressure wash in place of the evaporator, fan roller and pan.
- Sanitising solution on the clean surfaces.
- Outdoor unit, washed in place, from the balcony.
- See current rates on the Prices page.
What you can do yourself
- The ozone generator, since you have it, can serve for the fridge or the car, with the space empty and aired afterwards – not for the air conditioner.
- Filters every two weeks, 'Fan' before shut-off.
What NOT to do
- Do not stay in the room while the ozone generator runs – it is not 'fresh air', it is a lung irritant.
- Do not combine ozone with 'antibacterial' sprays – the reaction products are unknown.
- Do not believe in 'ozone sanitising' for AC – without washing, nothing is removed.
Prevention
A properly washed unit needs no gadgets. Annual sanitising, clean filters, drying before shut-off.
When to call us
0764 012 943, Monday–Saturday 08:00–20:00; Berceni is on our daily round.
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Read also
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- The air we breathe at home
- Symptoms of an uncleaned air conditioner
Sources (5)
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.