1. Mould on the coil and blower
Cold, damp surfaces inside the unit are perfect for mould. The fan blows the smell into the room.
How we fix itFull dismantle and chemical soakChemical overhaul from $150 →
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Why Does My Aircon Smell Bad?
The kind of smell tells you a lot about the cause. Here's what each smell usually means and how we fix it.
The short answer
A musty or sour smell usually means mould and bacteria are growing on the coil, blower or drain tray. It's very common in Singapore's humidity. Cleaning the filter helps a little, but a chemical overhaul is usually needed to remove the smell properly.
Quick diagnosis: what is your aircon doing?
| What you notice | Likely cause | Fix | Cost |
|---|---|---|---|
| Musty or damp smell | Mould on coil and blower | Chemical overhaul | from $150 |
| Sour smell when switched on | Bacteria in drain tray | Servicing or chemical overhaul | from $54.50 |
| Smoky or stale smell | Odours trapped in filter and coil | General servicing | from $54.50 |
| Rotten smell | Dead pest or debris inside the unit | Inspection and cleaning | $80 diagnosis* |
| Burning smell | Electrical fault or overheating motor | Switch off, call a technician | $80 diagnosis* |
Prices before GST. *On-site diagnosis is $80 for a split system and is waived when you book the repair.
5 causes of a smelly aircon, and how to fix each
2. Dirty filter
A dusty filter traps odours from cooking, smoke and pets.
How we fix itFilter wash in a general serviceAircon servicing from $54.50 →
3. Clogged drain tray
Stagnant water in the tray grows bacteria and smells sour.
How we fix itDrain tray and pipe flushingAircon servicing from $54.50 →
4. Pests inside the unit
Lizards or insects can get inside and die there, causing a strong rotten smell.
How we fix itInspection and deep cleanAircon repair: $80 diagnosis →
5. Electrical burning
A burning smell can mean overheating wiring or a failing motor. Switch it off right away.
How we fix itDiagnosis and repairAircon repair: $80 diagnosis →
What you can check yourself
- Wash the filters and let them dry fully.
- Run Fan mode for 15 minutes before switching off, to dry the coil.
- Air out the room with the windows open.
- Don't spray air freshener into the unit.
- Switch off at the isolator if you smell burning.
A burning smell is an electrical warning. Switch the aircon off at the isolator and don't use it until it's checked.
Aircon smells bad: FAQs
How much does it cost to fix a smelly aircon?
At JL Aircond, a chemical overhaul costs from $150 per unit and removes mould from the coil and blower. General servicing starts from $54.50. Prices are before GST.
Is a smelly aircon harmful?
Mould and bacteria blown into the room can trigger allergies, coughing and asthma, especially in children and older people.
Why does my aircon still smell after servicing?
General servicing cleans the filter and the parts you can reach. Mould deep inside the coil and blower needs a chemical overhaul to remove.
How do I stop my aircon from smelling?
Wash the filters often, run Fan mode before switching off, and service the aircon every 3 to 4 months.
Aircon still smells? We'll clean it properly.
Send us a photo of the blower on WhatsApp. We'll tell you if it needs servicing or a chemical overhaul.