Why Your Aircon Smells Musty — and How to Fix It

You turn on the aircon expecting cool, fresh air — and instead get hit with a damp, musty smell. Sound familiar? This is one of the most common complaints we hear at vFix, and the culprit is nearly always the same: mould and bacteria thriving in your evaporator coil and drainage tray.

What Causes the Musty Smell?

Singapore's humidity creates the perfect breeding ground for mould in any cool, dark, moisture-rich space — and your aircon's indoor unit is exactly that. When water from condensation doesn't drain properly, or when your filter is clogged with dust, the stagnant moisture turns into a mould farm.

Is It Harmful?

Yes. Breathing in air that passes through a mould-coated evaporator coil can trigger allergies, asthma, and respiratory infections — especially in children and the elderly. It's not a cosmetic issue you can ignore.

The Fix

• Chemical wash – A professional will dismantle the indoor unit and flush the coil with a cleaning agent that kills mould at the root.
• Drainage pipe flush – Ensures condensate water can drain freely and doesn't pool.
• Filter replacement or deep-clean – A clogged filter is often the primary cause of reduced airflow that lets mould grow.

How Often Should You Service Your Aircon?