LG CH35 Error in Bedok: Gas Leak at the Outdoor Connections
Aircon case in Bedok, Singapore: cooling loss traced to refrigerant leak at corroded outdoor unit pipe connections after targeted diagnosis checks.
Case Details

| Unit | LGWall-mounted |
|---|---|
| Age | 5 years old |
| Location | HDBBedok, Singapore |
| Reported | Unit showing CH35 error. Cooling had been fading over several weeks. A previous contractor topped up the gas, but the error returned within a month. A second top-up was done — same result. The pattern suggested a leak rather than a charge issue. |
What We Checked
- Refrigerant pressure was well below the operating range — consistent with CH35 activation.
- Outdoor unit pipe connections showed visible corrosion and green oxidation on both the gas line and liquid line fittings.
- Bubble test confirmed active leaking at the gas line connection where the fitting meets the outdoor unit valve.
- Indoor unit flare joints were clean and dry — no sign of leakage on the indoor side.
The Diagnosis
The gas was escaping through corroded pipe fittings at the outdoor unit. Moisture and airborne contaminants had been eating into the connection surfaces over several years. Each top-up restored pressure temporarily, but the leak rate was steady — the gas would drop back below the CH35 threshold within weeks.
What Fixed It
We welded the corroded connection, recharged the system to the correct pressure, and ran the unit to verify stable operation. We recommended monitoring the adjacent fittings — if one connection corroded, the others are likely aging at a similar rate.
Full cooling restored. The CH35 error cleared after recharging and did not return. No parts replaced — the fix was sealing the leak and restoring the charge.
Why This Happens
Why CH35 keeps coming back after a top-up.
- CH35 means the system pressure dropped below the safe operating threshold. A top-up restores pressure temporarily, but if the gas is leaking out, the error returns.
- Outdoor unit pipe connections are the most common leak point on LG systems — corrosion from rain, humidity, and airborne salt weakens the fittings over time.
- A top-up without leak tracing is not a fix. It buys time, but each cycle of pressure loss and recovery stresses the compressor and wastes refrigerant.
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