Aircon Running But Not Cooling? 8 Causes & Fix Guide (Singapore 2026)
January 18, 2026
Quick Summary
If your aircon is running but not cooling in Singapore, the issue may be dirty filters, low refrigerant gas, clogged coils, compressor faults, thermostat errors, or drainage blockage. This 2026 guide explains the real causes, what you can check yourself, and when to call for professional servicing.
Updated for 2026 • Singapore climate-focused • Step-by-step troubleshooting guide
It’s one of the most frustrating situations: your aircon is switched on, the fan is blowing, but the room is still warm.
In Singapore’s humid climate, aircon systems work hard almost daily. When cooling performance drops, the problem usually starts small — but ignoring it can lead to expensive repairs later.
1) Dirty Air Filters (Most Common Issue)
When filters are clogged with dust, airflow becomes restricted. Even though the fan is running, cool air cannot circulate effectively.
- Weak airflow from vents
- Room cools very slowly
- Higher electricity usage
Try cleaning the filters first. If performance does not improve, consider booking general aircon servicing.
2) Low Refrigerant Gas (Possible Leak)
Refrigerant gas does not “run out” under normal conditions. If cooling is weak, there may be a leak.
Common signs:
- Aircon blowing room-temperature air
- Ice forming on the indoor unit
- Hissing sound near piping
Proper inspection is required before topping up. Learn more about aircon gas top-up.
3) Dirty Evaporator Coil
Over time, dust and mould accumulate on the evaporator coil. This reduces heat exchange efficiency.
If your unit smells unpleasant or airflow feels restricted, you may need a chemical wash instead of normal servicing.
4) Faulty Compressor
The compressor is responsible for circulating refrigerant. If it fails, the fan may still run but no cooling happens.
This usually requires professional aircon troubleshooting.
5) Thermostat or Remote Setting Error
Sometimes the issue is simple:
- Set to fan mode instead of cool mode
- Temperature set too high
- Faulty remote sensor
Always double-check settings before assuming internal damage.
6) Blocked Drainage System
A clogged drainage pipe can affect internal humidity balance, leading to poor cooling and possible water leaks.
Severe buildup may require a chemical overhaul.
7) Outdoor Condenser Unit Overheating
If the outdoor unit is dirty or blocked by debris, heat cannot be released efficiently.
This significantly reduces cooling performance. Regular servicing prevents this issue.
8) Electrical or Capacitor Problem
Electrical components such as capacitors can weaken over time. When this happens, the compressor may not function properly.
Electrical issues should always be inspected by trained technicians.
When Should You Call a Technician?
- Aircon still not cold after cleaning filters
- Ice forming on indoor unit
- Frequent auto shut-off
- Strange noise or vibration
- Water leaking from unit
If you’re unsure about costs, you can refer to our aircon servicing cost guide (2026) before booking.
📌 Final Thoughts
If your aircon is running but not cooling in Singapore, don’t ignore early warning signs. Minor issues can quickly turn into expensive repairs if left unattended.
Regular servicing every 3–6 months keeps your system efficient, reduces electricity bills, and prevents sudden breakdowns.
Book Aircon Inspection Now
