Why has my new aircon never been cold since installation?
A new unit that has never cooled properly is not breaking down. Something was left unfinished at handover. Three commissioning steps get skipped, and each one leaves a system that runs without ever performing.
By Team Snowflake | Updated 19 Aug 2026
1. Charge never sized for the pipe run
A system that cools a little but never reaches target, from the very first day, often ran undercharged from the start. Outdoor units ship with a factory charge sized for a short pipe run. A longer run holds more refrigerant, so the installer has to add the difference. That step gets skipped.
How to tell
This path scales with distance. Unlike air in the line, the rooms furthest along the pipe run suffer most. Unlike a mode left on, changing settings makes no difference at all.
- It has never once cooled properly, from day one.
- The rooms furthest from the outdoor unit are the worst.
- It cools a little, so it does not look broken.
- The pipe run to the outdoor unit is long or goes around the flat.
How we confirm it
We measure the actual pipe length and compare the charge against what that run needs. The system is then weighed in correctly rather than topped up by feel.
A top-up by feel is not a fix on a new system. Without the pipe run measured, the charge is a guess, and an overcharged system cools worse under load than an undercharged one.
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2. Air left in the refrigerant line
Weak cooling that is the same in every room, on a system whose charge tests near normal, can mean air was never fully purged before charging. Tight service voids make that step awkward, so it gets rushed. Air mixed with refrigerant blunts how well the system absorbs and rejects heat.
How to tell
This path is even across the flat. Unlike an undersized charge, distance from the outdoor unit makes no difference to which room suffers. Unlike a mode left on, no setting change improves it.
- Cooling is weak evenly, not worse in one room.
- It has been like this since handover.
- The outdoor unit sits in a tight service void or riser.
- Nobody has ever reported the charge as low.
How we confirm it
We recover the charge, evacuate the line properly to pull the air out, then weigh in a fresh charge. The system is run afterwards to confirm it now holds target.
Adding more gas on top of trapped air does not fix this. The contamination stays in the circuit, so the cooling stays flat and you pay twice for the same visit.
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3. A demo or saving mode left on at handover
A unit that runs quietly and cools weakly, with nothing mechanically wrong, may still be in the mode someone used to demonstrate it. Installers show quiet operation on handover day, then move on without switching it back. The compressor stays capped, so the room never pulls down.
How to tell
This path is a setting rather than a fault. Unlike either charge problem, the unit responds immediately once the mode is cleared. It is also unusually quiet instead of running hard and failing.
- The unit is unusually quiet for how little it cools.
- An eco, quiet, or saving indicator shows on the remote or app.
- Nothing has ever sounded or looked wrong with it.
- It was installed in a rush, around a move-in date.
How we confirm it
We check the operating mode and any installer settings left in place. Normal operation is restored, then the unit runs to confirm it reaches target.
Do not pay for a gas top-up before the operating mode has been checked. A capped compressor looks exactly like a weak charge from inside the room, and the check costs nothing.
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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.