Why the Sea Air Is Killing Your Air Conditioner
Salt corrosion is the single biggest cause of early equipment failure on this coastline - and almost nobody is warned about it at the point of sale.
If you live in Summerstrand, Humewood, Jeffreys Bay or anywhere else within a few kilometres of the water, your air conditioner is in a fight it was not necessarily built for. Most people find out the expensive way.
What is actually happening
The outdoor unit of a split system is a heat exchanger. Hot refrigerant runs through copper tubing bonded to thin aluminium fins, and a fan pulls air across them to carry the heat away. It only works if air can move freely through those fins and if the metal can conduct heat efficiently.
Onshore wind carries a fine salt aerosol. It settles on the coil, absorbs moisture out of the air, and sits there as a mildly corrosive solution against two dissimilar metals in direct contact. That is close to a textbook setup for galvanic corrosion.
The aluminium fins degrade first. They whiten, then powder, then crumble away from the copper. As they go, two things happen at once: the surface area available to reject heat shrinks, and the gaps between fins clog with corrosion product so less air gets through.
Why you notice it as a bill, not a breakdown
This is what makes coastal corrosion so costly. Nothing breaks. There is no dramatic failure, no error code, no call-out.
Instead, the condenser cannot reject heat as well as it used to. Head pressure rises. The compressor works harder for the same cooling, draws more current, and runs longer to reach setpoint. The owner notices only that the room takes longer to cool than it used to, and that the electricity bill has crept up.
By the time anyone investigates, the unit has often been running inefficiently for two or three seasons, and the compressor has absorbed wear it should never have taken.
The timeline we see in practice. An uncoated condenser in an exposed beachfront position shows visible fin degradation within two to three years and meaningful capacity loss by year four or five. The same unit three kilometres inland can look almost untouched over the same period. Distance from the water is the single strongest predictor of how long your equipment lasts here.
What actually works against it
1. Coated coils, specified at purchase
Factory-applied coil coatings - usually a thin epoxy or hydrophilic blue coating over the fin stack - put a barrier between the salt and the metal. Specified up front, the cost difference is small relative to the unit. Retrofitted after corrosion has started, it is far less effective, because the damage is already done.
If you are buying for a coastal property, ask the question explicitly. Many installers will not raise it.
2. Washing the condenser, properly and often
Salt that is rinsed off cannot corrode. Twice a year is the realistic minimum within the coastal belt; quarterly is better in fully exposed positions. This is not a quick hose-down of the casing - it means getting water through the fin stack in the right direction, at a pressure that cleans without flattening the fins.
Flattened fins block airflow just as effectively as corrosion does, which is why over-enthusiastic pressure-washing by a well-meaning owner sometimes does more harm than the salt would have.
3. Thinking about where the unit goes
Placement is free and it matters enormously. A condenser on the seaward elevation of a building takes the full load. The same unit on the leeward side, or behind a screen wall that breaks the direct spray while still allowing airflow, has a materially easier life.
The constraint is that condensers need genuine airflow. Boxing one into a sealed enclosure to protect it from salt simply swaps corrosion failure for overheating failure. Screening has to be designed, not improvised.
4. Corrosion-resistant mounting hardware
Brackets and fixings rust out too. Stainless or properly galvanised hardware costs a little more and avoids the situation where a perfectly serviceable unit is hanging off a bracket that has lost its structural integrity.
What does not work
- Covering the unit. It traps moisture against the coil and blocks airflow. Unless the unit is out of service for a season, leave it uncovered.
- Ignoring it because nothing has broken. The whole problem is that nothing breaks until a great deal of money has already been wasted.
- Buying the cheapest unit on the basis that it will fail anyway. That is a self-fulfilling prophecy, and it means paying for installation labour twice as often.
A reasonable plan if you are near the sea
- Specify coated coils on anything new.
- Get the condenser washed at least twice a year - ideally going into summer and again at the end of it.
- Place the outdoor unit out of the direct onshore blast if the building allows it.
- Have the running current checked at each service. A unit drawing more than it used to for the same conditions is telling you its coil is struggling.
None of this is exotic. It is simply the maintenance regime this coastline requires, and it is the difference between replacing equipment every five years and keeping it for twelve.
We cover this as standard on our maintenance plans, and it is why our Summerstrand and Jeffreys Bay installations are specified differently to inland work.