I had it sanitised in March – do I need another at the end of summer?
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Rahova, flat, two Gree units (living room 12,000, bedroom 9,000), 5 years old. I had them sanitised in March by a company (with a cover, with water, looked fine). Now it is September and someone told me 'after the season you do it again, otherwise it sits dirty all winter'. Do you really need twice a year in a normal home?
What is really happening
'It sits dirty all winter' is a half-truth: a unit left wet in October keeps growing biofilm for the first weeks and then stops, because it is dry and cold; what matters is how you leave it – which is why manufacturers recommend running fan-only for a few hours before long periods of non-use. If you sanitise again next spring (April–May), the unit is clean exactly when it starts condensing. Alternatively, you can move the annual sanitising to September and start next summer clean; both are correct, what matters is one a year and no skipping.
- Start with the manufacturer’s instructions.
- Consider operating hours, environment and observations.
- Plan checks and record completed work.
One fixed interval does not suit every unit and home.
- Manufacturers recommend running the unit in fan-only mode for several hours to dry the interior before long periods of non-use, precisely to prevent odour and mould. [Daikin Europe, 2020]
- ASHRAE 62.1 requires visual inspection of cooling coils for cleanliness and microbial growth at least once a year and cleaning whenever fouling or microbial growth is observed. [ASHRAE, 2016]
- Daikin recommends periodic maintenance carried out by a specialist, in addition to user filter cleaning. [Daikin Europe, 2020]
- Mould does not grow below roughly 80% surface relative humidity, but the cold surfaces inside an air conditioner constantly exceed this threshold. [WHO / NCBI Bookshelf, 2009]
What we do on site
- If you want a check without paying for a needless sanitising: on a visit to a neighbour in your area we can look with a torch – if the roller is clean, we tell you to wait for spring.
- If the bedroom smells: bedroom only – sealed double cover, alkaline detergent, adjustable pressure wash, pan and hose, sanitising, filters, outdoor unit in place. See current rates on the Prices page.
- We note April 2027 in our calendar for both.
What you can do yourself
- Before the winter shutdown: filters washed and dried, the unit 2–3 hours on 'Fan' with the window open, then off from the remote (not at the breaker if the model has heating).
- Look at the roller with a torch now – that is the free test.
What NOT to do
- Do not pay for two sanitisings a year on a normal living room just because someone told you.
- Do not switch the unit off straight from 'Cool' with a wet evaporator.
Prevention
Normal home: once a year, spring or autumn, but always in the same period; children/allergies/all-night use: twice.
When to call us
0764 012 943, WhatsApp, Monday–Saturday 08:00–20:00; Rahova is 15 minutes away.
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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.