New BTO unit not cold traced to installer undercharge, not defective compressor
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
What client 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.
What we found
A unit that was never cold from day one is more likely a commissioning issue than a component failure. We checked the refrigerant charge against the pipe run before looking at the compressor.
- 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 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 we did
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.
Timeline
Day 1
New BTO unit never cold since installation — installer suspected defective compressor
Day 1
Checked refrigerant pressures and compared the factory pre-charge allowance against the actual pipe run before suspecting the compressor
Day 1
Refrigerant topped up to match pipe run length — unit started cooling immediately
What we learned
Why new installs sometimes feel warm — pipe length and charge.
- 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.
- 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.
Best next step
If your unit is behaving similarly, start with the service path that fits this case before approving broader scope.
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