Aircon Not Cold? Common Causes & How We Fix It

Why Your Aircon Is Not Blowing Cold Air

There are several reasons your aircon might stop cooling effectively. Some you can fix yourself; others require a professional technician. Here’s a comprehensive guide to help you troubleshoot.

DIY Checks You Can Try First

Before calling a technician, try these simple checks:

1. Check the thermostat — Make sure it’s set to cool mode and the temperature is below room temperature (try 22-24°C)
2. Clean the air filters — Dirty filters restrict airflow and reduce cooling. Remove, wash with water, dry, and reinstall
3. Check the outdoor unit — Ensure it’s not blocked by objects, plants, or debris
4. Look for ice — If you see ice on the indoor unit’s copper pipes or coils, turn off the aircon for 2 hours to let it defrost
5. Check the remote — Replace batteries and try again. Sometimes a simple reset helps

When to Call a Professional

If the DIY checks don’t solve the problem, the issue likely requires professional diagnosis. For a deeper look at all the possible reasons and fixes, read our complete guide to aircon not cold causes and fixes. Common causes that need a technician include:

Common Causes of Aircon Not Cold

1. Low Refrigerant Gas

The most common cause. When refrigerant levels drop due to a leak or natural loss, your aircon can’t absorb enough heat from the room. Signs include ice formation on the evaporator coil and the unit blowing room-temperature air.

Fix: Gas top-up from $50/unit, plus leak repair if needed.

2. Dirty Evaporator Coil

Even with clean filters, the evaporator coil inside your aircon accumulates dust and mould over time. A dirty coil can’t transfer heat efficiently, reducing cooling performance by up to 40%.

Fix: Chemical wash from $80/unit to deep-clean the coil.

3. Faulty Compressor

The compressor is the “heart” of your aircon — it circulates refrigerant through the system. A failing compressor may cause weak cooling, unusual noises, or the unit cycling on and off frequently (short cycling).

Fix: Compressor repair or replacement — we provide a quote after diagnosis.

4. Malfunctioning Thermistor

The thermistor is a temperature sensor that tells your aircon when to start and stop cooling. If it’s faulty, the aircon may not cool properly or may short cycle.

Fix: Thermistor replacement — a relatively quick and affordable repair.

5. Faulty PCB Board

The PCB (printed circuit board) controls your aircon’s electronic functions. A damaged PCB can cause erratic behaviour, including failure to cool.

Fix: PCB board replacement — cost varies by brand and model.

6. Frozen Evaporator Coil

When airflow is restricted (dirty filters) or refrigerant is low, the evaporator coil can freeze over. Ice insulates the coil and prevents it from absorbing heat.

Fix: Defrost the unit, then address the root cause (filter cleaning or gas top-up).

Our Troubleshooting Process

What Happens When You Call Us

1. WhatsApp us with a description of the problem and photos if possible
2. We schedule a same-day or next-day visit
3. Our technician diagnoses the issue — checking filters, refrigerant levels, compressor function, thermistor, PCB board, and electrical components
4. We explain the problem and provide an upfront repair quote
5. You decide — the troubleshooting fee ($40-$50) is waived if you proceed with our repair

Troubleshooting Pricing

Book Your Troubleshooting

WhatsApp us at +65 9427 3833 for same-day diagnosis. Describe the issue and we’ll send a technician as quickly as possible.