Condo unit not cold traced to dirty evaporator, not low gas
Aircon case in Katong, Singapore: cooling loss traced to evaporator coil heavily caked with grime from years of coastal humidity, blocking heat exchange despite normal gas levels after targeted diagnosis checks.
Case details
What client reported
The master bedroom aircon is blowing air but it is not cold at all. Another company came and said the gas had leaked because the evaporator coil was corroded from the salty air near the coast. They quoted for a coil replacement and full gas recharge. The unit is eight years old and the client was unsure whether to repair or replace.
What we found
Before assuming gas had leaked, we checked the evaporator coil condition and tested refrigerant pressures at the outdoor unit.
- Evaporator coil surface was heavily caked with a thick layer of sticky grime — almost no bare fin surface was visible
- Air was passing through the unit but barely making contact with the coil surface underneath the buildup
- Refrigerant pressures at the outdoor unit were within normal range — no gas leak detected
- After chemical wash, the coil surface was exposed and cooling output returned immediately
Years of coastal humidity had deposited a thick layer of grime over the evaporator coil fins. The buildup insulated the coil surface from the passing air. Even though the refrigerant charge was full and the compressor was running, heat exchange could not take place. The result was air blowing at room temperature.
What we did
GOOD NEWS — the evaporator coil did not need replacing and there was no gas leak. A chemical wash removed the grime layer and restored the coil surface. Full cooling returned without any parts or refrigerant work. Given the coastal location, chemical washes should be scheduled more frequently than standard intervals.
Full cooling was restored after the chemical wash. The unit ran through a complete cooling cycle and held the set temperature in the master bedroom. No coil replacement, no gas recharge. The client kept the existing unit.
Timeline
Day 1
Unit blowing but not cold — told gas leaked and coil corroded from salt air
Day 1
Inspected evaporator coil condition and checked refrigerant pressures before recommending any gas or coil work
Day 1
Chemical wash removed grime — full cooling restored with normal gas levels
What we learned
Coastal condos — why evaporator grime mimics low gas.
- When the evaporator coil is caked with grime, air passes over the surface but cannot exchange heat with the refrigerant inside. The unit blows room-temperature air even though the refrigerant charge is full.
- Condos near the coast are especially prone to this. Salt-laden humidity accelerates the buildup of sticky residue on the coil fins. Regular general servicing may not reach deep enough to clear it.
- A chemical wash dissolves the grime layer and restores the coil surface for heat exchange. If cooling returns after the wash, the gas was never the problem.
Best next step
If your unit is behaving similarly, start with the service path that fits this case before approving broader scope.
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