All Aircon Units Suddenly Not Cold: What Does It Mean?
Author : nocager215 cager | Published On : 26 Sep 2026
Aircon Not Cold
When all aircon units suddenly stop cooling, it can be frustrating, especially in Singapore's hot and humid weather. If several indoor units connected to the same system become warm at the same time, the problem may not simply be a dirty filter. It could indicate an issue with the outdoor unit, refrigerant system, electrical supply, thermostat settings, or a shared component.
For more details : your air conditioner not cooling properly?
Understanding the possible causes can help homeowners identify the problem quickly and know when professional aircon repair Singapore is needed.
Why Are All Aircon Units Suddenly Not Cold?
When multiple aircon units stop cooling simultaneously, it is useful to consider whether they share the same outdoor condenser or system. A multi-split aircon system may have several indoor units connected to one outdoor unit, meaning one major fault can affect multiple rooms.
Common causes include incorrect settings, power interruptions, outdoor unit problems, refrigerant issues, blocked airflow, or electrical faults.
Check the Remote Control Settings First
Before assuming there is a major fault, check each remote control.
Make sure the units are set to Cool Mode, rather than Fan, Dry, or another operating mode. Check that the temperature setting is lower than the current room temperature and allow the aircon several minutes to operate.
If every indoor unit has been changed to the wrong mode, all of them may appear to have stopped cooling even though the system itself is functioning.
Check the Power Supply
A recent power interruption or electrical trip can affect the operation of an aircon system.
Check whether the indoor units are receiving power and whether the relevant circuit breaker has tripped. If the breaker repeatedly trips after being reset, avoid repeatedly switching it back on. This can indicate an electrical or equipment fault that requires professional inspection.
Could the Outdoor Unit Be the Problem?
One of the most important things to consider when all aircon units are not cold is the outdoor condenser.
Outdoor Unit Not Running
The outdoor unit releases heat removed from your rooms. If its fan or compressor is not operating correctly, the indoor units may continue blowing air without providing effective cooling.
Possible causes include:
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Electrical component failure
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Fan motor failure
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Capacitor problems
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Control board faults
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Power supply issues
Do not open or attempt to repair the outdoor unit yourself, as it contains electrical components and refrigerant-related equipment.
Can Low Refrigerant Cause All Units to Stop Cooling?
Yes, depending on the aircon configuration, a refrigerant problem can affect multiple indoor units connected to the same outdoor system.
Refrigerant Leakage
Aircon refrigerant should remain within the sealed cooling circuit. If there is a leak, refrigerant pressure can become insufficient for effective cooling.
Possible signs include:
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Weak or warm airflow
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Ice forming on the indoor unit or copper piping
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Aircon taking much longer to cool
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Multiple connected units losing cooling performance
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Unusual hissing sounds in some cases
An aircon gas top-up should not automatically be considered the solution. If refrigerant is low, a technician should investigate whether a leak or another underlying issue is responsible.
Could Dirty Filters Cause Every Unit to Stop Cooling?
Dirty filters can certainly reduce cooling performance, but they are less likely to explain a sudden complete loss of cooling across every connected unit.
Restricted Airflow
A heavily clogged filter restricts air passing through the evaporator coil. This can reduce cooling performance and, in severe cases, contribute to coil icing.
Check the filters in each indoor unit. If they are visibly dusty, clean the washable filters according to the manufacturer's instructions and allow them to dry completely before reinstalling them.
If cooling remains poor after filter cleaning, the problem may involve deeper dirt, refrigerant pressure, the outdoor unit, or another component.
What If the Aircon Was Recently Serviced?
If all units suddenly become warm shortly after servicing, it does not necessarily mean the cleaning itself caused the problem.
Possible Reasons
The technician may need to investigate:
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Incorrect operating settings
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A pre-existing refrigerant leak
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A frozen evaporator coil
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Outdoor condenser problems
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Electrical or communication faults
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A faulty sensor or control component
A standard aircon servicing mainly addresses cleaning and maintenance. It cannot correct every possible mechanical or electrical fault.
What Should You Do When All Units Are Not Cold?
Start with simple checks before arranging a repair.
Step 1: Check the Operating Mode
Set the remote to Cool Mode and select a reasonable cooling temperature.
Step 2: Check the Filters
Inspect the indoor filters and clean them if they are heavily covered with dust.
Step 3: Check the Outdoor Unit
From a safe location, observe whether the outdoor unit appears to be operating. Do not climb onto ledges or dismantle the equipment.
Step 4: Look for Ice or Water Leakage
Ice on the indoor unit or copper piping, together with water dripping, can indicate restricted airflow or refrigerant-related problems.
Step 5: Arrange Professional Troubleshooting
If every connected unit remains warm after basic checks, professional diagnosis is recommended. A technician can inspect the system systematically instead of replacing parts or adding refrigerant without identifying the cause.
How Letscool Aircon and Services Can Help
For homeowners and businesses searching for aircon servicing and repair in Singapore, Letscool Aircon and Services provides aircon maintenance, troubleshooting, cleaning and repair solutions.
The technicians can assess issues affecting indoor units, outdoor condensers, airflow, drainage, refrigerant systems and other components. Depending on the condition of the system, services such as aircon general servicing, chemical wash, chemical overhaul, gas-related troubleshooting or component repair may be recommended.
Regular Aircon Maintenance Matters
Regular maintenance can help identify clogged filters, dirty coils, drainage problems and other developing issues before they result in major cooling problems.
For multi-split systems, maintaining both the indoor units and shared outdoor equipment is particularly important because a problem with a common component may affect several rooms.
Conclusion
When all aircon units suddenly become not cold, the cause may be more significant than a dirty filter. Incorrect settings, power issues, outdoor condenser faults, refrigerant problems, restricted airflow and electrical or control faults can all affect cooling performance.
If basic checks do not restore cooling, avoid repeatedly restarting the system or adding refrigerant without proper diagnosis. Professional aircon servicing and repair in Singapore can help identify the actual cause and determine the appropriate solution.
Letscool Aircon and Services can assist with aircon troubleshooting, servicing, cleaning and repair for residential and commercial properties across Singapore.
11 Mandai Estate,
#05-15 Eldix,
Singapore 729908
Mail ID: [email protected]
Service - Call: +65 9862 3678
Installation - Call: +65 94507178
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