Aircon Not Cooling? Here’s What to Do

Introduction

It’s a hot Singapore afternoon, and you turn on your aircon—only to realize it’s blowing warm air or not cooling as it should. We’ve all been there, and it’s infuriating. When your aircon fails to provide the relief you require, it’s essential to diagnose the reason behind it and act quickly.

In this article, we’ll discuss why your aircon won’t cool, typical warning signs, and how to resolve the issue—whether you’re in your home or a business building. We’ll also give you advice on when to get the experts involved.

1. Check the Thermostat Settings

It Might Be Simpler Than You Think

Begin with the fundamentals. Make sure the thermostat is set to “cool” and not on “fan” or “auto.” Check the temperature setting as well. Someone might have fiddled with it inadvertently.

Digital Thermostat Problems

If your thermostat is digital, the batteries might be dead, or the system might not be calibrated properly. Reset the system and test it again. If that fails, it will have to be replaced.

2. Dirty or Congested Air Filters

Constricted Airflow Means Poor Cooling

Filters fill up with dust, pet dander, and dirt over time, blocking airflow. Not only does this decrease cooling but also can freeze the evaporator coils and worsen performance even further.

Solution: Clean or Change Filters

A simple change of filters every 2–4 weeks (or replacing them every few months) will immediately boost your aircon’s performance. Most split systems on the wall have accessible filters that can be cleaned by hand.

3. Obstructed or Grubby Condenser Coils

The Outdoor Unit Matters Too

Your outdoor condenser unit on your aircon requires free airflow to dump heat. If it gets dusty, leafy, or grimy, it can’t cool.

What to Do
Switch off the power

Inspect for trash or blockages

Clean the unit with a soft brush or low-pressure water spray gently

If in doubt, it’s best to call a tech to do this safely

4. Low Refrigerant Levels

Refrigerant = The Cooling Agent

Refrigerant is the substance that absorbs and releases heat. If your aircon runs low on refrigerant, it will not cool properly and can even begin blowing warm air.

Warning Signs of Low Refrigerant:

Hissing or bubbling noises

Ice formation on the evaporator coil

High electricity bills

Longer cooling cycles

Important: Do Not Top Up Yourself

Refrigerant handling requires certification. If you suspect a leak or low levels, contact a licensed aircon technician immediately to avoid damaging the system or harming the environment

5. Frozen Evaporator Coils

Cold But Not Cooling

It may seem absurd, but if evaporator coils freeze, the system is unable to take in warm air, so no cooling. This usually occurs through limited airflow or refrigerant problems.

What Can You Do?

Shut down the unit and let it defrost (this could take a few hours)

Inspect and clean the filters

If it continues, call a professional

6. Electrical Problems or Defective Parts

Capacitors, Relays, or Sensors Might Be On the Fritz

Internal parts such as capacitors, contactors, or sensors can degrade over time. If they fail, your aircon might turn on but will not cool effectively—or won’t even start at all.

Warning Signs Are:

Inconsistent cooling

Clicking or buzzing sounds

Unit shutting down and cycling continuously

It is best to have these problems diagnosed and fixed by a professional technician.

7. Thermostat Sensor Misalignment

Reading the Wrong Temperature

If the room temperature sensor is misplaced or defective, your aircon may not operate at the proper settings. This will make it cycle incorrectly and not cool effectively.

The sensor may need to be repositioned or replaced by a pro if so.

8. Insufficient Unit Size for the Room

Undersized Units Can’t Keep Up

If your aircon isn’t the right capacity for your room size, it may struggle to cool effectively—especially during Singapore’s intense heat.

For example, a small unit in a large living room may run constantly without achieving the desired temperature.

Solution: Upgrade to the Right Size

Consult with an aircon specialist to ensure your system is suitable for your room’s square footage, ceiling height, and insulation.

9. Poor Maintenance History

Neglect Leads to Problems

Has your aircon been serviced in a while? Ones that are not serviced for extended periods tend to develop numerous problems—clogged filters, blocked drains, or worn components—all of which impact cooling.

Prevention is Key

Servicing every 3 months in Singapore keeps your unit humming along and performing its job well.

10. Drainage Issues or Leaks of Water

Cooling Could Cease Due to Safety Sensors

If the system identifies a clogged drainage pipe or internal leakage, it can shut down or cut off cooling to avoid damage.

Check for indicators such as:

Water dripping inside

Bad smells from the unit

Excessive dampness around the aircon

A technician can clean out the drainage pipe and remove any internal mould or residue.

When to Call a Professional
Although some of the minor problems (such as dirty filters) can be repaired by yourself, others need the hand of a licensed technician. Once you have checked the fundamentals and your aircon is not cooling yet, it’s time to call a professional.

Why Choose Cool & Clean in Singapore?

At Cool & Clean, we offer quick, reliable, and budget-friendly aircon servicing and repairs across Singapore. Our qualified technicians can detect and fix all manner of cooling problems—big or small.

We Provide:
Emergency aircon repair

Full system diagnostics

Gas top-up and leak checks

Regular maintenance packages

Friendly, responsive service

Prevention Tips Against Aircon Cooling Problems

Schedule regular maintenance every 3–4 months

Clean your air filters regularly

Don’t block airflow around indoor or outdoor units

Use the appropriate-sized unit for your area

Don’t put off servicing when you see early warning signs

Conclusion

If your aircon is not cooling, don’t sweat it—literally! Most issues can be diagnosed and fixed with a few easy checks or professional assistance. From grime buildup and low refrigerant to bad components, many cooling problems are preventable with good care.

Let Cool & Clean keep you cool all year long. From one-off repair to regular maintenance, our professionals are just a phone call away.

Schedule your aircon checkup today at Cool & Clean and re-establish your cool!