Why Is My Aircon Not Cold? 5 Common Reasons and Fixes in Singapore

If your aircon is running but not cooling the room, you're not alone. In Singapore’s hot climate, this is one of the most common complaints. It’s frustrating, especially when the heat is unbearable. Here's how to troubleshoot the problem and fix it fast.

Technician using a manifold gauge to check refrigerant gas levels of a wall-mounted aircon unit in a Singapore home

1. Low Refrigerant Gas (Aircon Gas Is Low)

A common reason your aircon is not cold is low gas. Refrigerant helps your system absorb heat. If the gas is low, the air blows but stays warm.

Signs to look for:

• Weak airflow

• Warm air from the vents

• Ice forming on the indoor or outdoor unit

Fix: You’ll need a technician to top up the gas. In Singapore, R32 and R410A are commonly used. Topping up is quick, but if you’ve done it recently, you might have a leak.

2. Dirty Air Filters

Dusty filters block airflow and reduce cooling. It’s easy to overlook but has a big impact on how well your aircon works.

What to check: Remove the front cover and inspect the filters. If they’re grey or dusty, they need cleaning.

Fix: Clean the filters every month with water. Let them dry before placing them back. For rental flats or HDB units, this is often the easiest fix.

3. Blocked or Clogged Condenser

Your outdoor unit (condenser) releases heat. If it’s blocked by dirt, plants, or laundry racks, the system can’t cool properly.

Fix: Make sure the area around the condenser is clear. If it's dusty or clogged, schedule a basic or chemical cleaning.

4. Thermostat Issues

If the thermostat is faulty or set too high, the aircon won't cool. Sometimes, the sensor is out of place and reads the wrong room temperature.

Fix: Check your thermostat settings. Try lowering the temperature. If there's no change, get a technician to inspect the sensor.

5. Faulty Compressor or PCB Board

The compressor is the heart of your aircon. If it fails, the system runs but doesn't cool. Another issue could be the PCB (printed circuit board), which controls how the unit operates.

Fix: You’ll need a professional technician. These parts are costly, so sometimes replacement is better than repair.

Bonus Tip – Use a Room Thermometer

Place a thermometer in the room to confirm if the aircon is cooling. Sometimes, it feels warm due to external heat or poor insulation, not the aircon itself.

A room thermometer reading 30°C beside an aircon, indicating a cooling issue despite the unit running

Don’t Ignore the Signs

Ignoring small issues leads to bigger problems later. If your AC cooling problem isn’t fixed after cleaning and checking settings, it’s time to call for servicing.

FAQ

Q1: Why is my aircon blowing air but not cold?

It could be low gas, dirty filters, or a faulty part like the compressor or PCB.

Q2: Can I top up aircon gas myself?

No. It requires proper tools and refrigerant handling by a licensed technician.

Q3: How do I know if my compressor is faulty?

Your unit may make loud noises, or it may run but not cool at all.

Q4: How often should I clean my filters?

Once every 3–4 weeks if you use your aircon daily.

Q5: Is this a common issue in Singapore?

Yes. Due to the heat and daily use, aircon not cold is one of the most frequent aircon servicing requests in Singapore.

Is your aircon not cooling? Contact Sky Blue Aircon Engineering to book a quick check-up and get it fixed before it worsens.