LG CH35 error in Bedok: gas leak at the outdoor connections
CH35 on an LG unit means low gas pressure. The question is where the gas went. Two earlier top-ups had held for only a few weeks each. That pattern pointed away from a charge problem and toward a slow leak the previous contractor never traced.
By Team Snowflake | Reviewed 13 Apr 2026
Case summary
LG Wall-mounted5 years oldHDBBedok, Singapore
- Concern
- The CH35 error kept returning after gas top-ups. Cooling faded again within weeks each time
- Previous advice
- Previous contractor topped up gas without leak tracing
- Found
- Refrigerant leak at corroded outdoor unit pipe connections
- Key check
- Bubble test at the outdoor unit connections confirmed active leak. Corrosion visible on both gas and liquid line fittings
- Result
- Full cooling was restored. The CH35 error cleared after the recharge and did not come back. No parts were replaced. The fix was simply sealing the leak and restoring the correct charge, which the earlier top-ups had never addressed.
What we were told
The unit was showing the CH35 error, and 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, with the same result. Paying twice for gas that did not last told us the charge was not the problem. Something was letting the refrigerant out.
What we checked
Two top-ups with the same outcome pointed to a leak, so the job was to find where it was rather than add more gas. We started at the outdoor unit connections, the most common failure point on LG systems of this age, and worked from there.
Gas pressure was well below normal, consistent with the CH35 error.
The outdoor pipe connections showed visible corrosion and green oxidation on both the gas line and liquid line fittings.
A bubble test confirmed an active leak at the gas line connection, where the fitting meets the outdoor unit valve.
The indoor unit pipe joints were clean and dry, which ruled out the indoor side as the source.
What we found
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, which is the corrosion the bubble test pinpointed. Each top-up restored pressure for a while, but the leak never stopped. Within weeks the gas dropped back below the level that triggers CH35, which is why the error kept coming back and cooling kept fading.
What fixed it
We welded the corroded connection to close the leak, then recharged the system to the correct pressure. We ran the unit to confirm the charge held and the cooling was stable. We also advised keeping an eye on the adjacent fittings. If one connection had corroded, the others were likely aging at a similar rate and could leak next.
Outcome
Full cooling was restored. The CH35 error cleared after the recharge and did not come back. No parts were replaced. The fix was simply sealing the leak and restoring the correct charge, which the earlier top-ups had never addressed.
What this case teaches us
A top-up that keeps fading means a leak, not a charge problem
- If gas runs out again within weeks of a top-up, the gas is escaping somewhere. A proper fix finds and seals that leak first.
- On LG units, the outdoor pipe connections are where corrosion tends to start. Green oxidation on the fittings is a clear warning sign.
- A top-up alone is not a repair when there is an active leak. Ask the contractor where the leak was traced before paying for more gas.
Related reading
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