Mould around air-conditioning units: the Cyprus connection
Why mould grows on and around air-conditioners
An air-conditioner cools a room by passing air over a cold coil inside the indoor unit, and that coil pulls water out of the air as it works. The water is meant to collect in a tray and run away through a drain hose. Dust drawn in with the air settles on the wet parts, and a damp, dusty, dark space is all mould needs. Add cold air blowing across nearby walls and ceilings, and the unit can encourage mould both inside its casing and on the surfaces around it.
Inside the unit or on the wall?
- Black specks on the louvres or the fan behind them: growth inside the unit, blown out each time it runs.
- A stain or patch directly below the unit: water escaping from a blocked or badly sloped drain, or an overflowing tray.
- Mould on the ceiling or wall where the airflow hits: surfaces chilled by the cold air, with room moisture condensing on them.
- Damp around the hole where the pipes pass through the wall: a gap letting outside air or rain in, or a pipe dripping inside the wall.
- A stale smell in the first minutes after switching on: damp inside the unit, even if you can't see any growth. Getting rid of a musty smell starts with finding where it comes from.
The Cyprus pattern
Units here work hard through the summer and then sit idle through autumn and spring, often with water left in the tray and a damp coil. Switched on again months later, they push out whatever has grown in the meantime. Apartments near the sea face the extra moisture of humid coastal air, and holiday homes left closed for months give a neglected unit plenty of time. Heating with the same unit in winter doesn't wet the coil the way cooling does, but it does keep circulating any dust and spores already inside.
What you can safely do yourself
Switch the unit off at the isolator or the fuse board first. Take out the filters, wash them as the manual describes, and let them dry completely before refitting. Wipe the louvres and casing with a damp cloth and a mild cleaner, wearing gloves and a mask, and clean any mould on the wall nearby the same way. Don't spray cleaners into the unit, where they can reach the electrics. While it's cooling, check that water drips steadily from the drain hose outside; if it doesn't, and the indoor unit leaks, the drain is probably blocked. If your model has a drying or self-clean setting, use it before switching off for the season. Cleaning the coil, fan and drain inside the unit is a job for an air-conditioning technician.
Musty air and your health
Mould blown out of a unit can irritate the nose, throat and airways, and it can make asthma and allergies worse; mould, asthma and allergies covers this in more detail. If anyone at home has symptoms that seem worse when the air-conditioner is on, mention it to your GP. In an emergency, call 112.
Stopping it coming back
Clean the filters often during the cooling season. Angle the louvres so the cold air doesn't blow straight onto a wall or ceiling, and avoid setting the temperature so low that surfaces near the unit feel cold to the touch. Have any gap around the pipe hole sealed. Before leaving a property closed for a long stretch, run the unit on fan or dry mode for a while so the inside isn't left wet.
When to get help
If mould keeps appearing on the walls near the unit after the filters are clean and the drain is clear, the problem may lie with the room, the wall or the unit itself. Where the moisture comes from is the first question, and the answer decides the fix. Moisture readings around the unit and in every affected room end with a room-by-room moisture map sent to your phone and a written report with the quote. For apartments that stand empty between stays, a monthly visit to keep humidity down catches regrowth early, with Home Protect from €45 a month.
Musty AC or mould around the unit? book an inspection from €75 or call +357 99 759144.