A bedroom unit that cooled well for three months after each service and then did not. It had been gassed four times in two years by three different companies, at about 900 rufiyaa a time.
We pressure tested it with nitrogen and left it on the gauge for an hour, which is the test that settles this and takes an hour that nobody wants to pay for. It lost pressure. The leak was in the thin copper of the outdoor coil where a pipe passed through a bracket, and the bracket had held salt water against the pipe for six years until it corroded through.
The coil was not repairable in a way we would stand behind. The honest options were a new coil at 4,200 rufiyaa fitted or a new unit at 8,900, on an eight year old machine, and we said so and let the family decide. They replaced the unit.
The important number here is 3,600 rufiyaa, which is what four top ups had cost for nothing. Every one of those companies knew the unit was leaking. Not one of them said so.