Air conditioners are essential appliances in homes, offices, and commercial buildings in Singapore. A malfunctioning air conditioner is, therefore, more than just an inconvenience in its tropical climate—it’s an emergency. If your aircon is running but not cold, the problem could range from a dirty filter to a refrigerant leak to more severe problems.
In this guide, we discuss some of the most common reasons why your aircon isn’t cooling, some practical DIY troubleshooting steps, and the situations in which you should call a professional. We will also go through Singapore-specific aircon maintenance tips for HDB, condo & commercial units.
Causes of Why Your Aircon Might Not Be Cooling Effectively
Below, we discuss some of the most common reasons as to why your aircon might not be cooling.
Dirty or Clogged Air Filters
One of the most common causes of aircon not cooling properly is that its air filters are dirty or clogged.
Why It Happens
Dust, pet hair, and pollen can accumulate in the air filters over time, blocking airflow.
When the airflow is restricted, it results in reduced cooling efficiency.
How to Fix It
Turn off the AC and locate the filter (usually, it is located behind the front panel).
Remove the filter and rinse it with water. If it appears greasy, you can clean it with mild soap.
Once washed and cleaned, let it dry completely before putting it back in the aircon
To ensure the best efficiency of the aircon, clean its filters every 2 months in Singapore’s dusty environment.
Low Refrigerant (Gas Leak)
Another common cause of airon being warm in Singapore is that its gas or refrigerant may have leaked. The refrigerant is the cooling agent in your AC and if it leaks, the aircon would not be able to function effectively.
Why Aircon Gas Leaks?
Poor installation
Corroded copper pipes
Wear & tear (especially in units 5+ years old)
Common Signs of Aircon Gas Leak
AC blows weak or warm air
Hissing/bubbling sounds near the indoor unit
Ice buildup on pipes
How to Fix It
Refrigerant handling requires a licensed technician and should not be taken on as a DIY task. You should call a professional aircon servicing solution to detect gas leaks and correspondingly top up the gas.
Faulty Thermostat or Remote Control
Another problem of the aircon that can cause it to throw warm air is that the thermostat could be faulty or your remote control settings might be off.
Why It Happens
Incorrect settings of the remote (e.g., it can be set to "Fan" mode instead of "Cool")
There could be dead batteries in the remote or certain other sensor issues.
How to Fix It
Check the AC remote: Replace batteries if weak.
Make sure that the mode setting is correct on the remote.
Reset the thermostat: Turn it off for 5 minutes, then restart.
Test with another remote (if available).
Singapore-Specific Tip: For Daikin/Mitsubishi aircon units, hold "Reset" for 3 seconds to reset the thermostat.
Blocked Condenser Coils (Outdoor Unit)
If the condenser coils in the outer unit are blocked, it can also cause the aircon to become faulty and not cool the room effectively.
Why It Happens
Dirt, leaves, or debris can clog the aircon’s condenser coils in the outdoor unit. This is especially common for HDB corridors in Singapore.
The blocked condenser coils reduce heat dissipation, resulting in poor cooling.
How to Fix It
Turn off the power to the outdoor unit.
Remove debris with a soft brush or vacuum.
Spray coils with a hose (gentle pressure only).
Hire a professional if the unit is hard to access (e.g., high-floor HDB).
Frozen Evaporator Coils
Sometimes, the aircon evaporator coils can freeze up, causing the aircon to become faulty.
Why It Happens
Low refrigerant or dirty filters can cause ice buildup in the evaporator coils.
Ice blocks the airflow, thus warm air blows out.
How to Fix It
Turn off the AC and let the ice melt (this can take up to 2 hours).
Replace filters and check refrigerant levels.
Call a technician if the issue persists.
Electrical Issues (Capacitor, Wiring, PCB)
Certain electrical issues can also reduce the aircon’s efficiency and cooling.
Why It Happens
Power surges or old wiring can damage aircon components.
This problem is typically common in older aircon units.
Signs of an Electrical Problem
The air conditioning trips the circuit breaker.
There is a humming sound, but the fan doesn’t spin.
How to Fix It
Electrical problems are best left for electricians and professionals to handle. Always call a professional technician to detect and fix electrical aircon issues.
Undersized or Aging Aircon
If the aircon is small as compared to the room size or if it is old, it would not be able to effectively cool the room.
Why It Happens
The aircon is too small for the room (e.g., 9,000 BTU unit for a 20 sqm bedroom).
Old aircon systems lose efficiency (especially 8+ years old).
How to Fix it
Upgrade to an inverter AC (saves 30–50% energy).
Choose the right BTU:
Room Size (Sqm) | Recommended BTU |
10–15 | 9,000 BTU |
15–20 | 12,000 BTU |
20–30 | 18,000 BTU |
DIY Fixes for Aircon Not Cooling (Step-by-Step Guide)
If your aircon is blowing warm air, try these quick DIY troubleshooting tips before calling a technician. Many common issues can be fixed at home with basic tools!
Clean or replace air filters, as clogged filters can block airflow, reducing cooling efficiency.
Check thermostat & remote settings, as wrong settings can prevent cooling. Ensure the mode is set to "Cool" (not "fan" or "dry"). Replace remote batteries if they are unresponsive.
Clear the blocked outdoor unit (condenser) as dirt/debris on the outdoor unit reduces cooling power. Turn off the power to the outdoor unit and remove leaves, dust, or cobwebs with a soft brush.
Inspect for ice buildup in the indoor unit. Turn off the AC, let the ice melt and clean the filters.
Ensure vents are open & unblocked as closed or obstructed vents restrict airflow. Vacuum vent grilles to remove dust.
Test the power supply & circuit breaker to see if the breaker tripped or if there is some loose wiring. Also, inspect the AC plug for damage.
When to Step DIY and Call a Professional in Singapore If the Aircon Is Not Cooling
Seek professional help if:
The AC still blows warm air after trying these DIY fixes.
You smell burning or gas.
You hear strange noises (hissing, grinding, buzzing)
You notice water leaking from the indoor unit
Pro Tip for Singapore Homes
Prevent future aircon issues with quarterly maintenance (aircon servicing + cleaning + chemical wash).
Upgrade old units (>8 years) to energy-efficient inverters (save 30% on bills).
Try these fixes first, but don’t risk further damage—call a licensed technician if unsure!
Conclusion
A non-cooling aircon in Singapore is usually caused by dirty filters, refrigerant leaks, or electrical faults. While some issues can be fixed DIY, complex repairs require professional help. Call 338 Aircon today for an extensive range of the best aircon services in Singapore.
338 Aircon Servicing Singapore provides an extensive range of Aircon Services including Aircon Servicing, Aircon Repairs, Aircon Installation of the best aircon brands, Chemical Overhaul, Gas Top-up, Aircon Leaking Water, and Aircon Not Cold Fix, and more. We have a team of professional technicians who are equipped with vast knowledge and experience in the Aircon industry.
It’s always a good time to talk about the common issues that aircon units have. We have over 15 years of experience in dealing with aircon works and have completed thousands of aircon works for both residential (Landed, Condo, and HDB) and commercial. We are a highly recommended Aircon Company in Singapore, with many delighted customers and reviews over the years on Google and Facebook.
Call or WhatsApp us at +65 88554141 / https://wa.me/6588554141 for a transparent quotation and honest pricing for all your aircon needs or We offer a fast and efficient service to serve any of your aircon needs!
Frequently Asked Questions
Why is my aircon running but not cold at all?
The most common causes of aircon not cooling are:
Dirty/clogged air filters
Low refrigerant (gas leak)
Faulty thermostat or remote settings
Blocked outdoor unit
How do I know if my aircon needs gas top-up?
Signs that your aircon needs gas top-up include:
Weak or warm airflow
Hissing/bubbling noises near the indoor unit
Ice buildup on pipes.
Why does my aircon take so long to cool the room?
This problem could likely be caused by:
Undersized unit (check BTU vs. room size)
Dirty filters/coils reducing efficiency
Poor insulation (sun-facing rooms in HDBs)
How much does aircon repair cost in Singapore?
Typical prices for aircon repair in Singapore include:
Service | Cost (SGD) |
Gas top-up | 120–250 |
Chemical wash | 80–150 |
PCB repair | 150–400 |
Compressor replacement | 400–1,200 |
Can I clean my aircon filters myself?
Yes, you can clean the aircon filters yourself. The steps include:
Turn off the AC.
Remove & rinse filters with water.
Dry completely before reinstalling.
How often should I service my aircon in Singapore?
Basic cleaning: Every 3 months (DIY filters + vents)
Professional servicing: Every 6–12 months (chemical wash, gas check)
Why is my aircon blowing weak airflow?
Possible causes include:
Clogged filters
Frozen evaporator coils
Faulty blower fan
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