Waterfront Shop Losing Cooling: Salt Corrosion on the Coil

A waterfront flat needing its cooling attended to more than once, with performance improving briefly each time and fading again. No refrigerant loss can be traced. The outdoor coil is discoloured and the fins look uneven.

The first thing to settle is whether the charge is actually low, because everything downstream depends on it. Where the pressures read correctly and the system is not short, the earlier top-ups were treating a symptom that had a different cause. A coil that has lost fin material rejects less heat, which reduces capacity in a way that briefly looks better after any intervention and then returns.

Salt-bearing moisture sits on aluminium fins and eats them from the surface inward. What is lost is the metal that carries heat from the refrigerant into the air, so the coil transfers less even when it is spotless. The effect grows steadily and never reverses, and because the symptom is reduced cooling it gets attributed to refrigerant every time. Nothing is escaping and nothing needs sealing.

What matters is how much fin material remains, so the coil gets assessed on that rather than on how it looks. The honest answer is either a replacement outdoor coil or an expectation set about what this unit can still deliver. Putting refrigerant into a system that measures correctly is the one thing guaranteed not to help. Repeating it is how a straightforward capacity problem becomes a long and expensive search for a leak that was never there.