New aircon never cooled properly: installer undercharged the gas
A brand-new unit had never cooled the bedroom to the set temperature. Two weeks after installation, the room still sat several degrees above target. The installer said new units need time to settle in. A correctly set up aircon should cool from day one.
By Team Snowflake | Reviewed 3 Mar 2026
Case summary
Daikin Wall-mounted2 years oldHDBTampines, Singapore
- Concern
- The earlier advice was that weak cooling from a new unit was normal and that it just needed time to settle in
- Found
- Refrigerant charge was low from installation. Unit was undercharged during setup
- Key check
- gas reading measured low for the site conditions. Confirmed undercharge, not a leak
- Result
- The bedroom reached the set temperature for the first time since installation. The recorded readings give a clear basis to raise the undercharge with the original installer.
What we were told
The unit was installed two weeks ago and has never cooled the bedroom properly. The room still felt warm even after the aircon ran for hours. The installer came back once and said new units need time to reach full performance.
What we checked
A brand-new unit that never reaches its set temperature has a short list of likely causes. The unit leaves the factory tested, so the compressor, coil, and control board are unlikely to be at fault. That points back to the installation, mainly the gas charge and the pipe connections. We measured the gas pressure on both the high and low sides first. The pressure reading shows straight away whether the charge matches the installed pipe length.
Gas pressure read well below the expected level for this model at these site conditions.
Both the high and low sides read low together, which points to too little gas rather than a blockage.
A leak check on every pipe joint and service port found nothing. The charge had simply been set too low at installation.
Airflow, filter, and coil were all normal. No blockage or mechanical fault, only the shortfall of gas.
What we found
The unit had been undercharged at installation. The gas charge was too low for the installed pipe run. The final charge was never checked against what this pipe length needs. Both pressure sides read low together, which means a plain gas shortfall, not a blockage or restriction. No leak was found at any connection. The aircon had run short of gas from its first day, which is why it never cooled to the set temperature.
What fixed it
We added gas slowly and watched how the system responded. The charge was brought up to the correct level for the installed pipe length. Once it reached the right range, we ran the unit under steady conditions and checked it again. The air at the vent came out clearly colder than before. We recorded the before and after readings so the client could take them to the original installer.
Outcome
The bedroom reached the set temperature for the first time since installation. The recorded readings give a clear basis to raise the undercharge with the original installer.
What this case teaches us
A new aircon should cool on the first day, not after settling in
- There is no break-in period for cooling. If a new unit never reaches its set temperature, the installation is the place to look first.
- Weak cooling from day one often means the gas charge was set too low for the pipe run, not a fault in the unit itself.
- Ask for the before and after gas readings in writing. They show whether the original installer charged the system correctly.
Related reading
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