Aircon New BTO Undercharged Refrigerant

Aircon case in Tengah, Singapore: cooling loss traced to refrigerant charge was insufficient for the actual pipe run length — the installer had not topped up beyond the factory pre-charge after targeted diagnosis checks.

Case Details

Reported: The aircon was installed when we moved into the BTO flat. It has never been cold. The air comes out but it is barely cooler than room temperature. The installer came back and said the compressor might be defective. He recommended filing a warranty claim with the manufacturer, but that could take weeks and we have been living without cooling since we moved in.
Unit: Midea · Wall-mounted · 1 years old
Location: HDB · Tengah, Singapore

What We Checked

Compressor was running and cycling normally — no unusual sounds, no tripping, no error codes.
Air from the indoor unit was noticeably warmer than expected, consistent with low refrigerant charge.
Pipe run from indoor to outdoor unit was longer than the standard factory pre-charge allowance.
After topping up refrigerant to match the actual pipe length, the indoor unit started blowing cold air within a short while.

The Diagnosis

The factory pre-charge in the outdoor unit was sized for a shorter pipe run than what the BTO layout required. The installer had not added the extra refrigerant needed for the longer run. The system was running with too little refrigerant from day one. The compressor was healthy — it just did not have enough refrigerant to work with.

What Fixed It

GOOD NEWS — the compressor was not defective. The system was simply undercharged for the pipe run length. We topped up to the correct charge based on the actual pipe run. The unit started cooling the room properly. No warranty claim was needed.

The master bedroom cooled down for the first time since the family moved in. The compressor was retained. No parts were replaced and no warranty claim was filed. The unit has been cooling normally since the top-up.

Why This Happens

Why new installs sometimes feel warm — pipe length and charge.

Every aircon unit ships with a factory pre-charge of refrigerant. That pre-charge covers a standard pipe run length, usually printed in the installation manual. If the actual pipe run is longer, the installer needs to add extra refrigerant to compensate.
When the charge is too low for the pipe run, the unit runs but the evaporator cannot absorb enough heat. The air coming out feels lukewarm rather than cold. The compressor is working, but there is not enough refrigerant circulating to cool the room.
Topping up to the correct charge for the actual pipe length restores full cooling. This is a commissioning step, not a repair — the compressor was never faulty.

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