Brand-new BTO Unit Never Felt Cold: Undercharged From Install
A brand new unit in a BTO flat had never cooled properly since installation. The installer suspected a defective compressor and suggested a warranty claim. But a unit that was never cold from day one is a different pattern from one that stopped cooling.
Case Details
| Unit | MideaWall-mounted |
|---|---|
| Age | 1 years old |
| Location | HDBTengah, Singapore |
| Reported | The aircon was installed when the BTO flat was handed over and had never been cold, the air came out but was barely cooler than room temperature. The installer returned and said the compressor might be defective, recommending a warranty claim that could take weeks. The flat had been without cooling since move-in. |
Diagnostic Turning Point
- Concern: Feared the brand-new compressor was defective and would need warranty replacement, which could take weeks.
- Key check: Checked refrigerant pressures and compared the factory pre-charge allowance against the actual pipe run before suspecting the compressor
What We Checked
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 Diagnosis
The factory pre-charge in the outdoor unit was sized for a shorter pipe run than what the BTO layout required. The installer hadn't added the extra refrigerant needed for the longer run. The system had been running undercharged from day one. The compressor was healthy but simply didn't have enough refrigerant to work with.
What Fixed It
The compressor wasn't defective. The system was simply undercharged for the pipe run length. We topped up to the correct charge for the actual pipe run, and the unit started cooling properly. No warranty claim needed.
The master bedroom cooled down for the first time since the family moved in. No parts were replaced, no warranty claim was filed, and 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.
Related Reading
Ready to Get Started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.