Troubleshooting
Aircon not cold? Here's what's actually wrong (and what it costs to fix)
An aircon that runs but does not cool is almost always one of seven things. Some you can fix in ten minutes; others need a technician. Here is how to tell which is which before anyone quotes you a repair.
First, rule out the easy stuff
In Singapore's humidity, a room with an open door will never hold temperature. Close it and give the unit 15 minutes before concluding anything.
- Mode is set to Fan or Dry instead of Cool
- Temperature is set higher than the room temperature
- Fan speed is on Auto and the unit is in low-demand mode
- A window or door is open, or the room gets direct afternoon sun
1. Clogged filters — the most common cause by far
In our climate, filters clog within four to six weeks. A blocked filter starves the evaporator of airflow, so the coil ices over and the air coming out is weak and lukewarm.
Slide out the filters, rinse under a tap, dry fully, and reinstall. If the airflow improves immediately, that was your problem — and it means your servicing interval is too long.
2. A frozen evaporator coil
If you see ice on the copper pipes or the fins inside the indoor unit, switch to Fan mode for 30–60 minutes to thaw it. Never chip the ice off.
Freezing is a symptom, not a cause — it is triggered by restricted airflow, a dirty coil, or low refrigerant. If it re-freezes after thawing, book a chemical wash or a gas check.
3. Low refrigerant (gas leak)
Aircon gas is not consumed — a system that is low has a leak somewhere. Signs are ice forming on the thin copper pipe at the outdoor unit, a hissing sound, and cooling that gets steadily weaker over weeks.
A top-up alone is a temporary fix. A proper job means pressure-testing, locating the leak, repairing it, then recharging. Anyone who tops up without leak-testing is selling you the same job again in three months.
4. A dirty condenser (outdoor unit)
The outdoor unit rejects heat. If its fins are packed with dust, leaves, or bird debris — very common in HDB service yards — it cannot dump heat and the whole system loses capacity.
Clear at least 30cm of space around it and make sure nothing blocks the fan discharge.
5. A failing compressor or capacitor
If the outdoor fan spins but the compressor never kicks in, or the unit hums and trips, the run capacitor is a common and inexpensive culprit.
A genuinely failed compressor on an older system often costs more to replace than the unit is worth — at that point a new install is the honest recommendation.
6. Undersized or overloaded system
A 9,000 BTU unit cannot hold a large living room, and a System 3 running all four rooms at once will underperform if it was specified for two.
If the unit has never cooled properly since installation, the issue is sizing, not a fault.
7. Blocked drainage causing a safety cut-out
Many units have a float switch that stops cooling when the drain pan fills. The fan keeps running, so the unit seems alive while producing no cold air. Clearing the drain line restores it.
What each fix typically costs
We quote before we start. If the honest answer is that a repair is not worth it, we will tell you that instead of selling you one.
| Issue | Typical fix | From |
|---|---|---|
| Clogged filter / light dust | General servicing | $40 per unit |
| Dirty coil, weak airflow | Steam cleaning | $66 per unit |
| Coil freezing, musty smell | Chemical wash | $90 per unit |
| Low gas | Leak test + gas top-up | Quoted after inspection |
| Compressor won't start | Capacitor replacement | Quoted after inspection |
Frequently asked questions
How often should I service my aircon in Singapore?
Every three to four months for a home used daily. Our 3-times-yearly contract covers that interval and includes a free mattress cleaning.
Does topping up gas fix an aircon that isn't cold?
Only if refrigerant is genuinely low, and only until the leak empties it again. Always insist on a leak test with any top-up.
Why is my aircon cold at night but not in the afternoon?
Heat load. If the system is marginally sized, it copes overnight but cannot keep up against afternoon sun. Servicing restores lost capacity; if it still struggles, the unit is undersized.
Need help with this? Message us — we quote before we start.
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