Aircon Outdoor Unit Gas Leak LG

The most common leak point on LG outdoor units is at the pipe connections — the flare joints where copper refrigerant lines meet the service valves. These joints rely on a precise metal-to-metal seal under high pressure. Any gap, scratch, or corrosion on the sealing surface creates a path for refrigerant to escape.

On some LG models, the connection layout positions these joints where moisture pools around them. In Singapore, where outdoor units face constant humidity, rain splash, and salt exposure near the coast, corrosion at those joints accelerates. Green or white oxidation around the pipe fittings is a visible sign that the sealing surfaces are degrading.

The second common leak source is inside the outdoor unit at brazed joints — the U-bends and return bends in the condenser coil. These joints are stressed by thermal expansion every time the system cycles on and off. Over thousands of operating hours, the copper fatigues where it meets the braze alloy, and a crack opens.

Singapore's outdoor environment is unusually hostile to refrigerant connections. Year-round humidity above eighty percent accelerates oxidation on copper tubing and creates the moisture needed for formicary corrosion — a type of subsurface attack that tunnels through copper from the inside, invisible until a pinhole breaks through.

Units on higher floors face additional wind-driven rain that hammers exposed joints. Coastal areas — East Coast, Pasir Ris, Sentosa — add salt particles that cling to condenser coils and copper fittings, causing pitting and galvanic corrosion where copper meets aluminium fins.

Unlike temperate climates where systems get seasonal rest, Singapore aircon runs heavily year-round. Every cooling cycle expands and contracts the copper lines. This constant thermal cycling fatigues brazed joints faster than in countries where systems shut down for winter.

Refrigerant does not deplete naturally. A sealed system should hold its charge for the entire lifespan of the unit. If a technician tops up gas and the cooling fades again within weeks, there is an active leak — and the top-up only masks it temporarily.

Each cycle of low refrigerant causes compounding damage. Refrigerant doubles as the compressor lubricant. When the charge drops, the compressor runs hotter, oil circulation drops, and internal bearings wear faster. This damage accumulates silently. The compressor may test fine today but fail months later from the cumulative stress of running on low gas.

The correct sequence is always: trace the leak first, repair it, then recharge to manufacturer specification. A technician who tops up gas without testing for leaks is treating the symptom, not the cause — and the cost of repeated top-ups eventually exceeds the cost of a proper repair.

A single corroded flare connection on otherwise healthy copper can be brazed and resealed. This is the simplest fix — the joint is accessible, the repair is testable with a nitrogen pressure hold, and the cost is a fraction of replacement. If the surrounding copper shows no spread of corrosion, brazing is a reasonable path.

When corrosion has spread along the pipe surface or multiple joints show degradation, brazing one spot often leads to a new leak nearby. At that point, replacing the affected pipework or the outdoor unit is more durable than chasing leaks one by one.

If the compressor has already been damaged from running on low refrigerant — confirmed by abnormal amp draw or elevated winding resistance — the outdoor unit needs replacement regardless of where the leak is. Fixing the leak on a damaged compressor delays the failure but does not prevent it.

CH35 on an LG system means the low-side refrigerant pressure has dropped below the safe operating range. The system flags this to protect the compressor from running dry. It confirms a significant refrigerant loss — not a marginal shortfall.

CH38 triggers when the refrigerant charge falls below the minimum threshold. The system locks out entirely and will not restart until the fault is cleared. At this stage, the compressor has been running on insufficient refrigerant and lubrication for some time.

When either code appears, do not reset and restart repeatedly. Each restart attempt on low refrigerant adds compressor stress. The right sequence is a full leak trace, pressure test, and compressor health check before deciding between repair and replacement. If the compressor tests healthy and the leak source is repairable, a proper fix is still viable.