Aircon Not Cold? Here's How to Fix It

Aircon running but the room's still warm? A dirty filter is usually the culprit. Try these fixes before calling anyone.

10 - 30 minutes Difficulty: Easy to Medium Last updated: March 2026

What You Can Fix Yourself

Check Your Air Filters First

Dirty air filters are the most common reason an aircon stops cooling properly. In Singapore, filters clog faster than you'd expect -- especially if you have pets or live near construction. To clean them: 1. Turn off your aircon and open the front panel (lift from the bottom on most models) 2. Slide out the mesh filters 3. Rinse under running water -- use a soft brush for stubborn dust 4. Let them dry completely before reinserting (15-20 minutes) 5. Close the panel and turn the aircon back on If your filters were visibly clogged, this alone may fix the cooling issue. Clean them every 2-3 weeks.

Check Your Temperature Settings

This sounds obvious, but it's worth checking. Make sure your aircon is set to **cooling mode** (not fan-only or dry mode) and the temperature is set to at least 2-3 degrees below room temperature. In Singapore, setting it to 24-25°C is typical. Also check that the fan speed isn't on the lowest setting — "Auto" mode usually works best.

Check for Blocked Airflow

Make sure nothing is blocking the indoor or outdoor unit: - **Indoor unit:** Curtains, furniture, or shelves too close to the unit restrict airflow - **Outdoor unit (condenser):** Check that it's not blocked by plants, boxes, or debris. The condenser needs free airflow to release heat Leave at least 15cm of clearance around the outdoor unit.

When to Call a Professional

Low Refrigerant (Gas Top-Up Needed)

If cleaning the filters and checking airflow doesn't help, your aircon may be low on refrigerant gas. Signs include: - Air blows but isn't cold - Ice forming on the copper pipes or evaporator coil - Hissing or bubbling sounds Refrigerant doesn't "run out" naturally — a low level usually means there's a leak somewhere. A technician will need to find and fix the leak, then top up the gas. **Cost:** $60-$150 depending on gas type (R22, R410A, or R32).

Dirty Evaporator or Condenser Coils

Over time, dust and grime build up on the evaporator coil (indoor) and condenser coil (outdoor), reducing cooling efficiency. This is especially common in Singapore's humid climate, where mould grows quickly on damp coils. A **chemical wash** ($80-$130 per unit) deep-cleans these coils and restores cooling performance. Recommended once a year.

Faulty Compressor

If none of the above fixes work, the compressor may be failing. The compressor is the "heart" of your aircon — it pumps refrigerant through the system. Signs of compressor failure: - Aircon runs but air is room temperature - Outdoor unit doesn't start or makes clicking sounds - Circuit breaker trips when aircon turns on **Cost:** $500-$1,200 for replacement. For older units (8+ years), it may be more cost-effective to replace the entire system.

When to Call a Pro

If cleaning filters and checking settings doesn't restore cooling within 30 minutes, or if you notice ice formation, hissing sounds, or the outdoor unit not running — it's time to call a professional.

Browse contractor directory →

Maintenance Tip

Service your aircon every 3-4 months in Singapore to prevent cooling problems. Regular servicing costs $40-$65 per unit — much cheaper than emergency repairs.