Is cold-then-warm the same as low gas?

Not always. Low refrigerant is one possible cause, but freeze-up, sensor faults, and outdoor unit dropouts can create the same pattern. The timing and airflow pattern matter.

Why does restarting the aircon make it cold again?

A restart can temporarily clear a protection state or reset a cooling cycle. It can also give a frozen coil time to thaw. The restart helps symptom reading, but it does not prove the cause.

Should I service the unit first?

If the filter is dirty, clean it first. Beyond that, intermittent cooling should be diagnosed based on the pattern before committing to service or part replacement.

What is the most useful thing to record?

A short video that shows the indoor airflow and the outdoor unit behavior when the air turns warm is very useful for triage.

Aircon Cold Then Warm

If your aircon cools well at first and then turns warm, the pattern matters more than the symptom name. This is usually an intermittent fault, not a simple cleaning issue alone.

Common Causes

A symptom is just a starting point. The same problem could be a quick fix or a major failure. The paths below show the most common causes, but only a proper check can prove what is really wrong.

Freeze-Up Pattern

Needs Diagnosis

The unit starts cold, then airflow and cooling drop as ice builds on the coil. This can happen when airflow is restricted or when refrigerant is below normal. The pattern changes during the same run, and that is the key clue.

Cooling is strong at first, then becomes weaker.
Airflow drops after the unit has been running for a while.
Water drips more after the unit is turned off and starts to defrost.

The Fix: We stop the freeze cycle first, then check airflow condition and refrigerant condition in the right order. If refrigerant is low, leak checks come before any top-up.

Watch out: Do not keep running a unit that is freezing. Compressor load increases while comfort drops.

Sensor Or Thermistor Instability

Needs Diagnosis

If the indoor sensor readings are unstable, the unit may think the room is already cool and reduce or stop cooling too early. The room then warms again and the cycle repeats.

Cooling returns after a restart but fades again with a similar pattern.
The unit cycles oddly without a clear room-temperature reason.
No obvious airflow blockage is found at the filter.

The Fix: We verify airflow first, then check sensor behavior and control response before recommending a thermistor or board repair.

Watch out: Airflow problems can mimic sensor faults. Do not approve sensor replacement before the airflow path is checked.

Outdoor Unit Load Or Protection Cycling

Needs Diagnosis

The outdoor unit may start normally but then stop under load. Cooling feels fine at first, then the room warms once the outdoor side drops out. This can involve fan, capacitor, compressor, or control faults.

Outdoor unit starts, then goes quiet while the indoor unit keeps running.
Cooling drops suddenly during operation, not gradually over many days.
The pattern is worse during hotter parts of the day.

The Fix: We check outdoor operation under load and confirm which component drops out before any repair is proposed.

Watch out: This pattern is often misread as low gas alone. The outdoor unit behavior during the warm phase is just as important as the room temperature.

Not Always A Fault - Normal Cycling Can Feel Like Warm Air

When the room reaches the set temperature, inverter systems can reduce output. If doors open often or heat enters quickly, the room may feel warm again soon. That is not always a fault if cooling returns normally.

How to tell

Cooling returns on its own without restarting the unit.
Airflow stays normal, but room heat rises due to doors, windows, or sunlight.
There are no error lights, smells, or strange sounds.

If cooling keeps dropping in the same pattern and does not recover normally, a fault check is needed.

What To Note Before You Contact Us

Observe one full cycle from startup to the warm phase:

How long it takes to change from cold to warm (rough estimate is enough).
Whether airflow also becomes weak, or airflow stays normal while air turns warm.
What the outdoor unit is doing when the air turns warm.
Whether a restart brings cold air back temporarily.

This pattern tells us whether to look at airflow freeze-up, sensor behavior, or outdoor load faults first.

Stop Using The Unit If You Notice These

Intermittent cooling is not usually urgent unless these signs appear.

Burning or electrical smell
Breaker tripping or repeated power cut
Heavy ice buildup on the pipe or indoor unit
Loud metal banging from the outdoor unit

Aircon Cold Then Warm

Common Causes

Freeze-Up Pattern

Sensor Or Thermistor Instability

Outdoor Unit Load Or Protection Cycling

Not Always A Fault - Normal Cycling Can Feel Like Warm Air

How to tell

What To Note Before You Contact Us

Stop Using The Unit If You Notice These

Common Questions

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