Small changes come first
You know how an aircon seems fine right up until the night it isn’t? In our experience, that’s rarely true. Most units give small warnings for weeks before they stop cooling or start leaking.
Brian started Cool Earth Aircon in 2007 as a one-man workshop, and the same pattern has shown up in thousands of HDB flats since. Catch the signs your aircon needs servicing early and a routine visit for aircon servicing in Jurong at S$50 for one unit is often all you need. Wait, and the same unit may need a wash or a repair.
Here are the seven signs we see most often, and what each one points to. If your aircon is due for servicing, at least one of them will probably sound familiar.
The 7 signs
1. Weak airflow
Weak airflow is the earliest and most common sign. Hold your hand in front of the vents on high fan. If the air feels weaker than it used to, the filter or coil is probably clogged.
Filters clog faster than most people expect. A 2026 maintenance guide from Cool Channels suggests rinsing the filter every two to three weeks on units used daily, between professional visits.
2. A dusty filter
A grey, furry filter means the unit is overdue. Lift the front cover and check what you see.
- Grey and furry filter: overdue for servicing.
- Clean filter, but dust on the fins behind it: dirt has moved into the coil, which only a technician can clean properly.
The cost of ignoring it shows up on your bill. The US Department of Energy says swapping a clogged filter for a clean one can cut an aircon’s energy use by 5 to 15%.
3. The room takes longer to cool
A slow-cooling room means the unit is working harder to move less heat. If your bedroom used to feel cool in ten minutes and now takes thirty, you’re paying for that extra effort in power every night.
Here’s a quick test. Billy Aircon, a Singapore servicing company, says a healthy system should blow air roughly 10 to 12 degrees cooler than the room. Hold a thermometer at the vent and compare.
4. A light musty smell
A faint damp smell for the first minute after switching on means mould is starting to grow. It usually sits on the wet coil or in the drain pan, and sometimes on the blower wheel too, according to a mould guide from Singapore’s Airple.
Catching it at this stage is cheap. Left alone, the smell returns faster and a general service stops being enough.
5. Dripping water
A few drops from the indoor unit, or a small stain on the wall below it, often means the drain line is starting to choke. A February 2026 guide from HomeJourney puts clogged drain lines behind roughly 60% of aircon leaks in Singapore.
Act on a small drip. It’s much easier to fix than a drain that has fully blocked and soaked your wall or bed.
Check the spot below the unit in the morning, when the stain is easiest to spot.
6. New noises
A rattle, hum or whistle that wasn’t there before can mean dirt is unbalancing the blower, or a part is working loose. A dirty blower is a servicing job. A loose part is a repair.
Take a 10-second video of the noise on your phone and send it to us. It helps us tell which one you have before we arrive.
7. Six months or more since the last service
If a unit used daily has gone six months without servicing, it is almost certainly running dirty, even if you notice nothing. This is the simplest answer to when to service aircon units in a home.
Singapore’s climate speeds the build-up. The Meteorological Service Singapore puts mean annual relative humidity at around 82%, and it often tops 90% before sunrise. Dust and moisture stick to a cold coil in that air.
- Used daily, bedroom or living room: book at least every six months.
- Used a few hours a week: a yearly check may be enough.
- Near renovation work: book sooner, as dust loads up the filter quickly.
Which signs mean servicing is enough?
Weak airflow, a dusty filter and slow cooling are usually fixed by general servicing. Use the table as a rough guide, then let the technician confirm on site.
| What you notice | Usually fixed by | Starting price |
|---|---|---|
| Weak airflow, dusty filter, slow cooling | General servicing | S$50 for 1 unit |
| Light musty smell, first time | General servicing | S$50 for 1 unit |
| Smell that returns soon after servicing | Chemical wash | From S$80 per unit |
| Black specks, sour smell, sludge | Chemical overhaul | S$130 to S$180 per unit |
| Steady dripping or stains | Leak repair | From S$60 |
| Grinding, buzzing or loud rattles | Repair | From S$60 |
When servicing will not fix it
If cooling is still weak a week after servicing, or the musty smell comes back within a month, the dirt is deeper than servicing reaches. A chemical wash cleans the coil and blower with the unit still on the wall.
Signs that point to a repair instead
Book aircon repair rather than servicing if the problem isn’t about dirt. These signs usually mean a fault in a part or the gas circuit:
- The unit blows warm air even with a clean filter
- There is ice on the copper pipes
- The outdoor unit does not start or buzzes loudly
- An error light is blinking
- The unit trips the power
Ice deserves special care. Billy Aircon warns that scraping frost off the pipes can puncture the soft copper, so switch the unit off and leave it alone.
Repair starts from S$60 with a fixed quote after diagnosis.
A quick self-check before booking
Two minutes is all it takes to find out whether your unit shows the signs your aircon needs servicing. Before you message us, go through this list:
- Switch the unit to cool, high fan, and feel the airflow.
- Lift the cover and look at the filter and the fins behind it.
- Sniff for any smell at start-up.
- Check the wall and floor below the unit for drips.
- Note when the unit was last serviced.
Send what you find, plus a photo, on WhatsApp. We will tell you whether general servicing, a wash or a repair fits, and give you a fixed price before anyone comes over.
Not sure how often to book? See how often to service your aircon.