Health & home

Is Your Aircon Making Your Family Sick?

That musty smell when the aircon kicks on isn't just unpleasant. It can be a sign of mould and bacteria growing inside the unit — and being blown into the air you breathe.

ServisYou 14 June 2026 6 min read

We tend to think of the aircon as making a room cleaner and more comfortable. But a neglected unit can do the opposite: become a damp, dark home for mould and bacteria, then circulate them through the room every time it runs. If anyone in your home has allergies, asthma or a sensitive chest — especially young children or older relatives — it's worth understanding.

Why aircons grow mould

An air-conditioner constantly pulls moisture out of the air, so the inside of the unit is damp by design. Add the dust that collects on the coil and blower wheel, and you have exactly what mould and bacteria need to thrive: moisture, warmth and something to feed on. In Malaysia's humidity, this happens faster than in drier climates. Once colonies establish on the coil and in the blower wheel, the airflow carries their spores and odour straight into the room.

The tell-tale sign: a musty, sour or “old cloth” smell when the aircon first switches on. That smell is the by-product of mould and bacteria. It's the unit telling you it needs a proper clean — not a problem to mask with air freshener.

How it can affect health

Poor indoor air quality is recognised as a contributor to respiratory irritation, and mould exposure is associated with allergy and asthma symptoms. A dirty aircon blowing spores into a closed, air-conditioned room can worsen these for sensitive people. Common patterns families notice include a stuffy or runny nose, sneezing, throat or eye irritation, or asthma that feels worse indoors than out — particularly overnight in an air-conditioned bedroom.

This isn't cause for alarm, and we're not here to diagnose anyone — if a household member has persistent symptoms, a doctor is the right person to see. But a clean aircon removes one avoidable source of indoor irritants, which is well within your control.

Other signs worth checking

  • Black or greenish spots on or around the air outlet vents.
  • Symptoms that ease when you leave the room or switch the unit off.
  • A smell that returns a day or two after you've tried to freshen it — a sign the source is still inside.

What actually fixes it

Masking the smell doesn't work, because the mould is still there. Two things do:

  • A chemical wash. This is the real fix. It strips and cleans the coil and blower wheel where the mould lives — a surface clean can't reach it. If your unit smells musty, this is what clears it. See chemical wash vs standard cleaning.
  • A monthly filter rinse, then regular servicing. Cleaning the filter yourself each month and keeping to a sensible servicing schedule stops the dust-and-damp build-up from coming back.

A clean aircon is a health measure, not just a comfort one — especially in a home with kids, older relatives or anyone with asthma. A chemical wash from a ServisYou verified partner clears the mould properly: fixed price, outdoor unit included, 7-day guarantee.

Common questions

A dirty aircon can circulate mould spores, bacteria and dust into the air you breathe, which is associated with allergy, asthma and respiratory irritation — especially for children, older people and anyone with a sensitive chest. It's one avoidable source of indoor irritants. For persistent symptoms, see a doctor; to remove the source, clean the unit.
The clearest sign is a musty or sour smell when the unit starts up. Others include black or greenish spots near the air vents, and symptoms that ease when you leave the room or turn the unit off. A smell that returns after freshening means the source is still inside.
Usually not fully. Mould grows on the coil and inside the blower wheel — parts a standard surface clean doesn't reach. Clearing it properly takes a chemical wash, which strips and cleans those internal parts.

Clear the mould properly

A chemical wash reaches where mould actually grows. Fixed RM280/unit, outdoor included, 7-day guarantee. Book a verified partner.

Book a Chemical Wash

Keep reading

Chemical Wash vs Standard The deep clean that actually removes mould — and when you need it. How Often to Service Keep mould from coming back with the right schedule. Aircon Leaking Water? Damp and blocked drains feed mould — here's the fix.