Which is the dirtiest part of the unit? The filters look clean
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Berceni, Emil Racoviță street, 1984 block, 12,000 BTU Midea, 4 years old. I wash the filters often and they are almost clean. So where does the smell come from and why does everyone insist on sanitising? Genuine curiosity: where do the bacteria actually live in a unit?
What is really happening
Finding microorganisms in a study of air conditioners does not show that this particular unit caused an infection or symptoms. The condition of the unit, moisture, ventilation and other indoor sources need to be assessed separately. Cleaning is maintenance, not a medical treatment or a guarantee of sterile air.
- A typical split recirculates room air.
- Ventilation introduces outdoor air through a suitable solution.
- The condensate pan of household units had the highest bacterial load (~12,300 CFU/cm²), over 20 times the 500 CFU/cm² limit for public spaces. [Frontiers in Public Health / PubMed Cent, 2024]
- Dense bacterial biofilm (~11,000–47,000 CFU/cm²) dominated by Methylobacterium forms on aluminium heat exchangers. [Current Microbiology / PubMed Central, 2012]
- 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]
- Air conditioners in Japanese homes host distinct bacterial communities on each component, showing that every part must be cleaned separately. [CORE (open access repository), 2015]
What we do on site
- We open and show you the three 'dwellings': the pan (sludge), the evaporator (film) and the roller (dots/felt).
- Collection cover; cleaning solution applied to each separately.
- Pressure wash, in place, component by component; pan and hose rinsed until the water runs clear.
- Sanitising solution on all three.
- Outdoor unit on the balcony, washed in place.
- See current rates on the Prices page.
What you can do yourself
- Keep doing the filters – they slow evaporator fouling.
- 'Fan' 20–30 minutes before shut-off – dries the evaporator and the pan.
- Once a month, unit off, shine your phone light behind the filters.
What NOT to do
- Do not push sticks, brushes or the vacuum towards the pan – it is thin plastic and cracks.
- Do not pour disinfectant into the pan – it runs out through the hose in 2 minutes and leaves residue.
- Do not confuse 'clean filters' with 'clean unit'.
Prevention
Plan maintenance according to the appliance manual and what is found during inspection. Keep any medical follow-up separate; cleaning does not guarantee that symptoms will resolve.
When to call us
0764 012 943 / WhatsApp, Monday–Saturday 08:00–20:00. Berceni.
Maintenance does not replace medical care. CDC: mold and health · EPA: moisture and mould
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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.