The Short Answer: Every 3 to 4 Months
If you’re wondering how often you should service your aircon, the answer for daily use is every 3 to 4 months. That’s the interval we recommend for aircon servicing in Serangoon and across Singapore.
We’re the Serangoon service of Cool Earth Aircon, which Brian started in 2007 as a one-man workshop. Units here run almost every day of the year, in hot and humid air. That combination clogs filters and coils much faster than in cooler countries.
Most manufacturer manuals suggest servicing once or twice a year. Those intervals suit climates where the aircon sits idle for months. A bedroom unit in a Serangoon HDB flat that runs every night does more work in three months than some units overseas do in a year.
Why humidity makes dirt build up faster
Humid air leaves a wet film on the coil, and dust sticks to it. Here’s how it builds up:
- Warm humid air passes over the cold evaporator coil every time the aircon runs.
- Moisture condenses on the coil and drips into the drain pan.
- Dust that gets past the filter sticks to the wet coil and forms a film. Mould grows on that film.
- Over weeks, the film thickens, the coil absorbs less heat, and the drain pan collects slime.
In Singapore, this happens all year round. The Meteorological Service Singapore puts mean annual relative humidity at around 82%, and it barely changes from month to month. There’s no dry season to break the cycle.
Rule of thumb
The more hours a unit runs each day, the sooner it needs servicing. Daily-use bedroom and living room units: every 3 to 4 months. Light-use rooms: every 6 months.
Servicing Intervals by Room and Use
Most daily-use units need servicing every 3 to 4 months, and the room decides the rest. Here is how we plan it for Serangoon homes and businesses:
| Room or site | Typical use | How often to service |
|---|---|---|
| Master bedroom | Every night, 6-10 hours | Every 3 months |
| Other bedrooms used daily | Every night | Every 3 to 4 months |
| Living room | Afternoons and evenings | Every 3 to 4 months |
| Guest room or study | A few times a month | Every 6 months |
| Office | 8-10 hours on weekdays | Every 3 months |
| Shop or eatery | Long opening hours, grease or dust | Every 2 to 3 months |
If you work from home, the living room or study unit may run 10 hours a day. Treat it like a bedroom unit and service it every 3 months.
Between visits, give the filters a quick look. NEA’s household energy-saving guidance says to check the air-conditioner filter once a month and clean or replace it when necessary. A rinse every few weeks keeps dust off the coil for longer.
Signs You Are Overdue
If it has been more than 6 months since the last service, you’re overdue. Even if you can’t recall the date, the unit will tell you. Watch for:
- Weak airflow from the vent, even on high fan speed
- Dusty filters that look grey within a couple of weeks
- Slow cooling, where the room takes much longer to get cold than it used to
- A light musty smell when the unit starts
- Water dripping or pooling near the indoor unit, often a sign of a choked drain line
- More than 6 months since the last service
We cover these in more detail in our guide to the signs your aircon is due for servicing.
Does Your Home Type Change the Interval?
Only a little. The interval depends mostly on how long each unit runs, but the type of home affects what builds up and where:
- HDB flats. Bedroom units in 2 to 4 unit flats run every night. Older flats often have long drain runs through trunking, so the drain line flush at each 3-month service matters more than in newer homes.
- Condos. Most condos run inverter multi-split systems, where one outdoor unit serves several rooms. If one indoor unit is neglected, that room cools poorly even when the others are fine, so service every indoor unit on the same cycle.
- Landed homes. With 6 to 10 units, it is easy for spare-room units to be forgotten. Units that sit unused stay damp inside and grow mould, so include them in every visit even if they are rarely switched on.
- Shops and eateries. Long opening hours, dust and kitchen grease clog filters fastest of all. Every 2 to 3 months is usually right.
For HDB owners, the drain line deserves extra attention. HDB’s renovation guidelines require aircon condensate to discharge into a nearby floor trap, so a choked line has nowhere safe to go. Standing water can also become a mosquito breeding spot. Since July 2020, NEA has fined first-time household offenders S$200 for a single breeding habitat, and S$300 for multiple habitats found in the same inspection.
Does Regular Servicing Save Power?
Yes, it helps. A clean coil and clean filters let the unit move heat with less effort. When the coil is coated, the compressor runs longer to reach the set temperature, and your bill creeps up with no change in how you use the aircon.
The US Department of Energy says replacing a dirty, clogged filter with a clean one can lower an air conditioner’s energy use by 5% to 15%. That’s the same reason NEA asks households to check filters monthly.
Regular servicing won’t turn an old unit into a new one. It keeps a healthy unit running the way it should.
When a Normal Service Is Not Enough
A normal service is not enough once a unit has gone a long time without care. General servicing cleans the filters, checks and cleans the coil, flushes the drain line and tests the unit. It keeps a healthy unit healthy, but it may not shift what has built up deep inside a neglected one.
Here is how we decide on the next step:
| Symptom | Better option |
|---|---|
| Normal upkeep, no problems | General servicing every 3 to 4 months |
| Cooling stays weak, or a musty smell comes back after a normal service | Chemical wash |
| Heavy mould, a sour smell, or jelly-like sludge in the drain pan | Chemical overhaul |
Sticking to a 3-to-4-month cycle is the best way to avoid needing either.
How to Stay on Schedule Without Thinking About It
The hardest part of servicing every 3 months is remembering the date. Most people only book when something goes wrong, by which time the unit needs more than a service.
Two simple ways to stay on track:
- Set a calendar reminder every 3 months, and rinse the filters yourself every few weeks in between.
- Sign up for an annual servicing contract. You get four visits a year with priority booking, a reminder before each one, and a lower total price than four single visits. Contracts start from S$200 a year for 2 units.
For a typical Serangoon flat with 2 to 4 units, general servicing costs S$55 for 2 units, S$70 for 3 and S$85 for 4, with a fixed quote and no callout fee.
So, how often aircon servicing should happen in your flat comes down to one number: every 3 to 4 months for daily-use units. If you’re not sure when your units were last serviced, book a general service now and start the 3-month clock from there.
