Why aircon mould grows in Singapore homes
Mould needs moisture and something to feed on, and an aircon in a humid Singapore home has both. As the unit cools, water condenses on the cold coil and drips into the drain tray. If the tray or drain pipe is slow, water sits inside and the unit stays damp.
Dust is the food: what gets past the filter settles on the wet coil and blower wheel, and mould grows on it.
How you use the unit matters too. A unit left off for weeks stays closed up with moisture inside, and a bedroom unit run only at night stays humid all day. If you notice a stale odour rather than spots, see why your aircon smells musty.
Where to look
With the power off, lift the front panel and use a torch:
- Louvres. Dark patches along the flaps are usually easy to wipe.
- Filter. A grey layer is mostly dust, but a filter that stays damp can grow mould too.
- Blower wheel. Black specks on this drum-shaped fan behind the louvres are the usual sign of mould in aircon blower wheels.
- Drain tray. It sits under the coil and is mostly hidden. Slime or standing water here often goes with leaks.
Black spots in aircon louvres are often only the visible part. The blower wheel, the back of the coil and most of the drain tray cannot be reached without dismantling the unit.
What you can clean safely
DIY aircon mould cleaning covers only what you can reach from the front: the filters, louvres and front panel. A clean filter also keeps dust off the coil and blower. For more on the filters, see how to clean your aircon filter.
Always switch off the power first. EMA's electrical safety advice covers safety around electricity at home and notes that all homes must have a residual current circuit breaker (RCCB).
- Switch off the power. Turn the unit off with the remote, then at the isolator.
- Wash the filters. Slide the filters out and rinse them under running water with a little mild detergent.
- Wipe the louvres and panel. Use a soft cloth dampened with mild detergent and wrung out well.
- Dry fully. Let the filters dry in the shade. A filter refitted damp gives mould a fresh start.
- Refit. Slide the filters back in and close the front panel.
- Run fan mode. Switch the power back on and run fan mode for a while to dry the inside.
A filter indicator light is a reminder to clean the air filter. Daikin's FAQs say to reset it with the filter button on the remote after cleaning. Daikin also notes that its separate air purifying filter is not washable and is replaced every three months or when it turns dark, so check your manual before you wash a filter you do not recognise.
When to book a chemical wash or overhaul
Book a technician if you see black specks on the blower wheel, if a musty smell returns soon after you clean the filters, or if water leaks from the indoor unit.
Not every drip or smell means mould. Daikin's FAQs say water dripping from the outdoor condensing unit is normal condensation, and that a foul smell is usually room, furniture or cigarette smells absorbed into the unit and blown back out. Daikin advises getting a qualified serviceman to service the unit, and notes that skipping regular servicing can clog the cooling coil and lead to water leakage.
A chemical wash cleans the coil and nearby parts, usually without fully dismantling the unit. An aircon chemical overhaul takes the unit apart so the blower wheel and drain tray can be cleaned, which suits heavy mould in the blower. Ask each company what its service covers.
Published chemical wash rates
38 companies publish a chemical wash rate per indoor unit. Their lowest published rates run from S$50 to S$160 per unit, with S$80 in the middle. That middle figure is one company's real published rate, not an average. Some lines are "2+ units (price each)" or "From" prices, so read each line as printed.
FROM THE HOMEZYPRO DIRECTORY
Published chemical wash rates
For the most common unit (per unit), the lowest published rates from 38 companies run from S$50 to S$160. Each figure is one company's own advertised rate with its conditions, not a market average or a quote.
See 38 published chemical wash rates and sources
| Company | Service as listed | Rate | Source |
|---|---|---|---|
| Afix.sg | Chemical wash, 2+ units (price each) | S$50 per unit | afix.sg |
| Airple | Aircon Chemical Wash | S$55.55 per unit | airple.com.sg |
| Above All Aircon Pte Ltd | Aircon chemical wash | S$60 per unit | aboveallaircon.com.sg |
| Aircon Express Pte Ltd | Chemical wash, below 18k BTU | S$60 per unit | airconexpress.sg |
| Snowflake Services LLP | Chemical wash, wall-mounted, 3+ units (price each) | From S$60 per unit | snowflakeaircon.sg |
| Surecool Aircon | Chemical wash | S$60 per unit | surecool.com.sg |
| 7Days Aircon Servicing Pte Ltd | Aircon Chemical Wash - 6 Fancoil units & above (price each) | S$65 per unit | airconservicing.org |
| A-Max Aircon | Chemical wash | S$65 per unit | amaxaircon.com |
| Aircon Service, Chemical Wash & Overhaul Yishun | Chemical Wash, 6-9 FCU (price each) | S$69.55 per unit | airconserviceking.com |
| Fast Aircon Service Singapore | Aircon Chemical Wash in Singapore | From S$70 per unit | fastairconservicesg.com |
| Kool & Kleen Aircon Servicing | Chemical wash | From S$70 per unit | kool.com.sg |
| Cool Earth Aircon | Chemical wash | From S$80 per unit | coolearth.com.sg |
| Cooling Guard Pte Ltd | Chemical wash | S$80 to S$130 per unit | airconservicessg.com |
| Ecocool Aircon Pte Ltd | Eco Chemical Wash | S$80 per unit | ecocoolairconpteltd.com |
| Jex Aircon Private Limited | Chemical Wash | From S$80 per unit | jexaircon.sg |
| Jk Aircon Specialist | Chemical wash, 1 fan coil (one-time) | S$80 per unit | jkairconspecialist.com |
| Konnect Aircon Servicing | Chemical Wash | From S$80 per unit | konnect.com.sg |
| Techmen Engineering Pte. Ltd. | Chemical wash, 9,000 BTU, 1 unit | S$80 per unit | peakcool.sg |
| Sky Blue Aircon Engineering Pte. Ltd. | Eco-chemical wash, single unit | From S$80 per unit | skyblueaircon.com |
| TJ Aircon Engineering | Chemical Wash, 1 unit (9,000-18,000 btu) | S$80 per unit | tjaircon.com.sg |
| Airmaxx Aircon Pte Ltd | Chemical wash 9k-12k BTU, 1 unit | S$85 per unit | airmaxxaircon.com |
| City Cooling Pte Ltd | Chemical wash, fan coil (no dismantling) | S$85 per unit | citycoolingengr.com.sg |
| Non-Stop Cooling Aircon Service Singapore | Chemical Wash | S$85 per unit | nonstopaircon.com |
| Thetop Aircon Service | Chemical wash FCU, 1 unit | S$85 per unit | thetop.com.sg |
| Lion City Air Conditioner Services | Chemical wash | S$87.20 per unit | lioncityaircon.sg |
| Aircon Fairprice Engineering Pte Ltd | Chemical Wash | From S$90 per unit | airconfairprice.sg |
| Airemax Aircon Pte. Ltd. | Chemical Wash | S$90 per unit | airemaxsg.com |
| Bencool Services | Chemical wash, 9000 BTU (1 HP) unit | S$90 per unit | bencoolservices.com.sg |
| Goodcool | Aircon Chemical Wash 9K-15K BTU | S$92.65 per unit | bestairconservicing.com |
| GoodCool Aircon Servicing & Repair Singapore | Aircon Services - Professional Aircon Chemical Wash Singapore | From S$92.65 per unit | goodcoolsg.com |
| Easy Cool Engineering Pte Ltd | FCU chemical wash, non-dismantle, 9k and 12k | S$100 per unit | easycool.sg |
| Same Day Aircon Servicing Repair | Chemical wash | From S$100 per unit | urgentairconservicing.sg |
| Cool Aircon | Chemical wash | S$110 per unit | coolaircon.sg |
| 3322CoolAir Pte Ltd | Chemical Wash | From S$120 per unit | 3322coolair.com.sg |
| 338 Aircon | Chemical wash 9K BTU | S$120 per unit | 338aircon.sg |
| VFix Aircon Pte Ltd | CU Chemical Wash | S$120 per unit | vfixservice.sg |
| Gradecool Air-Condition Pte Ltd | Chemical wash (page scope includes re-installation of evaporator unit) | S$150 per unit | gradecool.com.sg |
| Solar Air-Conditioning & Electrical Services P/L (Eubiq SG) | Chemical Wash | From S$160 per unit | saces.sg |
Preventing mould coming back
Mould returns when the conditions that fed it stay the same. These habits help:
- Clean the filters regularly. Less dust then reaches the coil and blower wheel.
- Run fan mode after cooling. Let the fan run for a while before you switch off, so the inside dries.
- Keep the drain clear. Dripping from the indoor unit is often the first sign of a slow drain.
- Book regular servicing. A technician can flush the drain and clean parts you cannot reach. See chemical wash vs general servicing to decide which you need.
NEXT STEP
See aircon servicing companies with their published prices, the areas they say they cover and their sources.
Compare aircon servicingOutside the unit, NEA advises against placing trays or containers under or above an aircon unit, as they can let mosquitoes breed. If a tray is needed, NEA says to use HDB's patented air-conditioner tray and check it so the drain point does not choke and hold water.
When a service is due, you can compare aircon servicing companies by their published prices.
Health and comfort notes
Mould and dust in an aircon can bother some people, especially those with allergies or asthma, and a mouldy unit can leave a room smelling stale. Clean filters and regular servicing help keep the air fresher.
This page is general information, not medical advice. If anyone at home has symptoms that worry you, see a doctor.
Questions
Are the black spots in my aircon mould?
Often, yes. Black specks on the louvres or the blower wheel are commonly mould growing on dust and moisture, though some marks are plain dirt. You can wipe the louvres yourself with the power off, but the blower wheel needs a technician.
Can I spray a mould cleaner into my aircon?
It is safer not to. Liquid sprayed into the unit can wet parts that must stay dry and overload the drain tray, and it misses most of the mould inside. Clean only the filters, louvres and panel yourself, and leave the rest to a servicing company.
Does a chemical wash remove mould?
A chemical wash can remove mould from the coil and the parts it reaches, usually without fully dismantling the unit. Heavy mould on the blower wheel or in the drain tray may need a chemical overhaul, where the unit is taken apart.
How do I stop mould coming back?
Clean the filters regularly, run fan mode for a while before you switch off, and keep the drain clear so water does not sit in the tray. Regular servicing lets a technician clean the parts you cannot reach.
Is mould in the aircon harmful?
Mould and dust can bother people with allergies or asthma, and a mouldy unit can make a room smell stale. This page is not medical advice. If anyone at home has symptoms that worry you, see a doctor, and have the unit cleaned.
Why does mould come back after servicing?
Moisture and dust return after any clean. A routine service may not reach the blower wheel or drain tray, and units run only at night or left off for long periods stay damp. Clean filters, fan mode and the right service all help.
Prices come only from the sourced company rates in the HomezyPro directory, shown with each company and its source.
Practical guidance for planning a home job in Singapore. Company prices come from the HomezyPro directory, each linked to its source; rules and safety points link to the agency or manufacturer that sets them. This is not a site inspection, a quote or professional advice for your home.
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