LG CH35 Error In Bedok: Gas Leak At The Outdoor Connections
CH35 on an LG unit means low refrigerant pressure. The question is where the gas went. In this case, corroded pipe connections at the outdoor unit were leaking slowly enough that earlier top-ups masked the actual leak.
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. |
Diagnostic Turning Point
- Concern: CH35 error kept returning after gas top-ups. Cooling would fade again within weeks
- Previous advice: Previous contractor topped up gas without leak tracing
- Key check: Bubble test at the outdoor unit connections confirmed active leak. Corrosion visible on both gas and liquid line fittings
What We Checked
Two top-ups with the same outcome pointed to a leak. We started at the outdoor unit connections, the most common failure point on LG systems of this age.
- 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.
Related Reading
Ready to Get Started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.