What you'll notice
Visible frost or ice on the thin copper line where it enters the outdoor unit, often with poor cooling indoors.
Why it happens
Low refrigerant charge or restricted airflow across the indoor coil. Both drop the evaporating pressure far enough that the line temperature falls below freezing and moisture in the air condenses and freezes on it.
How we fix it
We check filters and indoor airflow first, since a blocked filter is the cheaper and more common cause, then measure system pressures and superheat to establish whether the charge is genuinely low before touching the gas.
Still not working?
If the checks above haven't restored your refrigerant circuit & gas lines, this usually needs a technician. Our Aircon Regas & Gas Top-Up service covers exactly this fault — from R900, quoted upfront.