Why Is My Aircon Not Turning On? A Complete Troubleshooting Guide

Few situations are as frustrating as pressing the remote after a long day and realizing your air conditioner

is not turning on. In Singapore’s humid climate, reliable cooling isn’t just a comfort — it’s a necessity.

This article provides a detailed troubleshooting guide for homeowners and businesses to uncover the reasons why your AC is not turning on, the steps you can take yourself, and when to bring in a professional. By the end, you’ll know how to fix common issues and how to prevent them in the future.

Quick Takeaways

• An aircon not turning on often relates to electrical supply, thermostat, or airflow issues.

• Simple checks, such as replacing batteries, resetting the circuit breaker, and cleaning the air filter, can quickly resolve the issue.

• Complex issues, such as compressor faults, wiring problems, or refrigerant leaks, require professional attention.

• Preventive maintenance keeps your air conditioning unit reliable and reduces the risk of breakdowns.

• If your air conditioner still won’t turn on after troubleshooting, book an aircon technician to avoid further damage.

8 Common Reasons Why Your Aircon Is Not Turning On

Your AC is made up of multiple interdependent parts. If one fails, the whole system can be affected.

Below are the most common culprits when your air conditioner is not turning on.

1. Power Supply Problems

Power supply is the first thing to check if your aircon won’t turn on. A tripped circuit breaker, loose wiring, or a blown fuse could mean the unit isn’t receiving power.

👉 How to fix:

• Reset the circuit breaker by flipping it off and back on.

• Check the plug and socket connection.

• If the problem persists, turn off the main power to see if resetting helps.

⚠️ If sparks, burning smells, or repeated tripping occur, this is a sign of deeper electrical trouble that a professional must fix.

2. Thermostat Malfunctions

Your thermostat is the control brain of your air conditioning unit. If the thermostat is not working correctly, the air conditioner will not respond.

👉 Common checks:

• Verify that your thermostat is set to cooling mode and the temperature is lower than the current room temperature.

• Check the batteries. A blank or flickering screen usually means they need replacement.

• Test the display by adjusting settings to see if the system responds.

If your thermostat continues to fail even after battery changes, calibration or replacement may be required.

3. Dirty or Blocked Air Filter

The air filter is often overlooked but is critical to proper airflow. When clogged with dust or dirt, it can prevent the AC from starting because the unit overheats or goes into safety mode.

👉 How to fix:

• Remove the air filter and gently clean it with water.

• Replace the filter if it is too dirty or damaged.

• To prevent recurring issues, clean or replace filters every one to three months in Singapore, where dust and humidity build up quickly.

4. Frozen or Dirty Condenser Coils

The condenser plays a vital role in releasing heat from your unit. If the condenser in the outdoor unit is dirty, the AC may overheat and shut off. If it freezes over, your aircon won’t be able to turn on properly again until it’s fixed.

👉 How to:

• Inspect the outdoor unit for ice or visible dirt.

• Ensure the area around the condenser has good airflow.

• If ice forms repeatedly, refrigerant leaks may be the cause, and only a professional can resolve it.

5. Capacitor or Motor Failure

The capacitor gives the compressor and fans an initial power surge to start. If it fails, the unit may hum but still won’t turn on. Likewise, if the fan motor burns out, your AC unit won’t function.

👉 To fix: Listen for buzzing or clicking noises. Homeowners should not attempt to repair capacitors and motors without proper safety precautions. A professional must do a replacement.

6. Refrigerant Leak

Without enough refrigerant, your air conditioner is unable to maintain pressure, and eventually, the unit may be unable to turn on at all.

👉 Warning signs:

• Reduced cooling before complete failure.

• Hissing sounds or ice forming on pipes.

• High electricity bills without cooling.

Refrigerant leaks can be harmful to health and the environment. Only licensed technicians should repair leaks and refill the gas.

7. Control Board or Electrical Issues

Sometimes the issue isn’t with the visible components but the control board inside. When the wiring, relays, or control circuits fail, the AC does not work.

👉 How to fix: This is not a DIY repair. Handling live circuits is dangerous. A professional is required.

8. Drainage Blockages and Float Switch

When the drainage system clogs, water builds up and activates a float switch that shuts down your unit to prevent flooding. This is a common issue in humid Singapore where algae and dust quickly clog pipes.

👉 How to:

• Use a vacuum or cleaning solution to clear the drainpipe.

• Schedule regular drainage maintenance.

DIY Troubleshooting Steps Before Calling a Professional

Before spending money on service calls, you can perform these simple checks:

1. Replace batteries in the remote controller.

2. Confirm the plug is secure and reset the circuit breaker.

3. Clean or replace the air filter to restore airflow.

4. Verify your thermostat settings.

5. Inspect the outdoor unit to see if debris is blocking it.

6. Reset your aircon if your unit is equipped with a reset button.

⚠️ When to stop DIY: If you notice electrical burning smells, leaking refrigerant, or motor issues, stop immediately and call for professional help.

When to Call a Professional

If your air conditioner isn’t turning on after these steps, a deeper problem exists. Common cases include:

• The compressor failing to start.

• Circuit breaker tripping repeatedly.

• Unusual buzzing, grinding, or humming noises.

• Wiring faults or control board failures.

• Ongoing refrigerant leaks.

An expert can diagnose the issue accurately, replace faulty parts, and ensure your unit operates safely again.

How to Prevent Future Problems

The best way to avoid emergency breakdowns is through prevention. In Singapore’s tropical climate, air conditioners need more frequent servicing due to dust, heat, and high humidity.

• Schedule professional servicing 2–3 times a year.

• Clean the air filter every 4–6 weeks.

• Keep the outdoor unit clear of plants, leaves, and clutter.

• Have refrigerant levels checked yearly.

• Inspect and service your thermostat and electrical connections.

• Consider annual maintenance contracts with trusted companies to prevent surprises during peak hot months.

These steps extend the life of your air conditioning system and ensure you are always prepared for the next heatwave.

Quick Reference Table

Cause	DIY Fix	When to Call a Pro
Tripped circuit breaker	Reset breaker	If breaker trips repeatedly
Thermostat malfunction	Change batteries, recheck settings	If still unresponsive
Dirty air filter	Clean/replace filter	If airflow still blocked
Frozen/dirty condenser	Inspect, remove debris	If coils keep freezing
Capacitor/motor failure	None	Replacement needed
Refrigerant leak	None	Technician recharge & repair
Control board/electrical	None	Must be repaired safely
Drainage issues	Clean pipe	If blockage keeps recurring

FAQs

Q1: Why is your aircon not turning on after a power outage?

Sometimes after an outage, the unit remains locked for safety. Switch it off, wait 5–10 minutes, then restart. If it still doesn’t turn on, the surge may have damaged components.

Q2: If your air conditioner won’t turn on, should you attempt electrical repairs?

No. Electrical repairs involve live circuits and can be dangerous. Always leave electrical work to licensed technicians.

Q3: Can clogged drainage pipes stop your aircon from working?

Yes. When water cannot flow out, the float switch activates to protect your home from leaks, causing the unit to stop turning on.

Q4: How can I tell if the compressor is faulty?

If your air conditioner is not turning on but you hear clicking or humming noises, the compressor may be struggling. This requires replacement.

Q5: What is the lifespan of an air conditioning unit in Singapore?

Most units last 8–12 years if maintained properly. Regular servicing extends lifespan, while neglect reduces it drastically.

Q6: Can regular maintenance reduce costs in the long run?

Yes. Cleaning and preventive checks reduce the risk of expensive repairs and extend the life of your unit, helping you save over time.

Q7: How much does it cost to fix an aircon that isn’t turning on?

Minor issues like dirty filters or drainage problems may cost as little as $50–$80. Larger repairs such as compressor replacement can cost several hundred dollars.

Final Thoughts

There are several reasons why your AC may not turn on, ranging from simple solutions, such as cleaning the air filter, to more complex issues, including refrigerant leaks or compressor failure.

While you can handle basic checks yourself, it is always advisable to call a professional for electrical or gas-related issues.

If your air conditioner isn’t turning on despite troubleshooting, don’t panic. At 338 Aircon, our expert technicians are trained to diagnose and fix air conditioners across Singapore quickly.

Whether you live in an HDB flat, a condo, or manage an office, we’ll ensure your unit is restored to peak performance.

📞 Call 338 Aircon today for reliable aircon servicing and enjoy uninterrupted comfort in your home or workplace.