Air conditioners are essential in Singapore’s hot and humid climate. When your aircon suddenly starts behaving oddly, such as blowing strong air from the left and right sides but little or no airflow from the middle, it can be frustrating and uncomfortable.
Many homeowners assume the blower fan is dirty and proceed to clean it, only to discover that the problem remains. If your aircon initially blows air normally but the middle section loses airflow after a few minutes, there may be a deeper issue that requires attention.
In this guide, we’ll explore the common causes of uneven airflow in air conditioners and what Singapore homeowners can do to resolve the problem.
Understanding Uneven Airflow in Air Conditioners
Under normal conditions, your aircon should distribute cool air evenly across the entire indoor unit. If certain sections have stronger airflow while others appear weak or blocked, it is often a sign that something inside the system is restricting airflow.
One common scenario experienced by homeowners is:
- Airflow is normal immediately after startup.
- The centre section blows air for a short period.
- After a few minutes, airflow from the centre becomes weak or disappears.
- Air continues to blow from the left and right sections.
This symptom can indicate several underlying issues.
Dirty Evaporator Coil
One of the most common causes of uneven airflow is a dirty evaporator coil.
While many homeowners regularly clean their air filters and even wash the blower wheel, the evaporator coil is often overlooked. Over time, dust, dirt, and airborne particles accumulate on the aluminium fins of the coil.
In Singapore’s humid environment, moisture continuously condenses on the evaporator coil during operation. When dirt combines with moisture, airflow can become restricted, particularly in heavily clogged areas.
As the aircon runs, the centre section of the coil may become increasingly blocked by moisture-laden dirt, resulting in reduced airflow through that section while the sides continue to operate normally.
Signs of a Dirty Evaporator Coil
- Weak airflow despite a clean blower fan
- Aircon not cooling as effectively as before
- Uneven airflow across the indoor unit
- Musty odours from the aircon
- Higher electricity consumption
A professional chemical wash is often required to thoroughly clean the evaporator coil and restore proper airflow.
Partial Ice Formation on the Coil
Another possible cause is partial icing of the evaporator coil.
When refrigerant levels are low or airflow is restricted, parts of the coil may become excessively cold and begin to freeze. Ice formation can block airflow through specific sections of the coil, causing certain areas of the aircon to stop blowing air effectively.
In many cases, the aircon starts normally because the coil is initially free of ice. As the system continues operating, frost gradually develops and airflow becomes restricted.
Symptoms of Coil Icing
- Airflow decreases after several minutes of operation
- Water dripping from the indoor unit
- Aircon not as cold as usual
- Ice or frost visible behind the filters
- Uneven airflow across different sections
If icing is suspected, it is advisable to arrange for a professional inspection to check refrigerant levels and system performance.
Blocked Drainage and Excess Moisture
Singapore’s high humidity means air conditioners remove large amounts of moisture from indoor air.
If the drainage system is partially clogged, excessive moisture can accumulate within the unit. This can contribute to airflow restrictions and encourage mould or slime buildup on the evaporator coil.
Regular servicing helps keep the drainage system clear and reduces the likelihood of moisture-related airflow issues.
Faulty Sensors or Thermistors
Modern air conditioners rely on sensors to regulate cooling performance and prevent freezing.
A faulty thermistor may cause the evaporator coil to become excessively cold, leading to uneven cooling and airflow problems. While less common than dirty coils or refrigerant issues, sensor faults can produce similar symptoms.
Professional diagnostics are usually required to confirm this issue.
How to Troubleshoot the Problem
Before calling a technician, homeowners can perform a few basic checks:
1. Inspect the Air Filters
Dirty filters reduce airflow and can contribute to coil icing. Clean them if necessary.
2. Check for Ice Formation
Open the front panel after the aircon has been running for 20–30 minutes. Look for frost or ice on the evaporator coil.
3. Observe Cooling Performance
Is the room still cooling effectively, or has cooling performance declined? Poor cooling may indicate refrigerant-related issues.
4. Listen for Unusual Sounds
Strange noises can point to airflow restrictions or internal component problems.
When Should You Call a Professional?
If you’ve already cleaned the air filters and blower wheel but airflow remains uneven, professional servicing is recommended.
A qualified technician can:
- Inspect the evaporator coil
- Check refrigerant pressure
- Clean clogged components
- Identify thermistor or sensor faults
- Perform chemical washing if necessary
Ignoring airflow issues can reduce cooling efficiency, increase electricity bills, and place additional strain on your aircon system.
Infinity Air for Aircon Troubleshooting in Singapore
If your aircon is blowing air from the sides but not the middle, don’t wait until the problem worsens.
With over 20 years of experience and more than 15,000 completed servicing jobs, Infinity Air has helped countless Singapore homeowners diagnose and resolve aircon airflow problems, cooling issues, water leaks, and system faults.
Whether your unit requires a professional inspection, chemical wash, or repair, our experienced technicians can restore your aircon’s performance and help you stay comfortable all year round.
Contact Infinity Air today via WhatsApp 9383 6574 for reliable aircon servicing and troubleshooting solutions anywhere in Singapore.
