LG System-3 Losing Gas: Leak at Outdoor Unit, Not Inside Walls

• –Refrigerant pressure was below normal operating range across the system.
• –Pipe run extended from the outdoor unit at the rear of the house through concealed channels to three indoor units on the upper floor.
• –Outdoor unit pipe connections showed corrosion and green oxidation at the joints.
• –Nitrogen pressure test on the concealed pipe section held steady — no loss detected in the walls.
• –Nitrogen pressure test on the outdoor unit connections showed a drop, confirming the leak location.

We confirmed the concealed piping was not leaking and no wall work was needed. The leak was at the accessible outdoor connections. We welded the corroded joints and recharged the system. Because the outdoor unit was six years old and the corrosion was localised to the connection area, a weld repair was a reasonable first step before considering outdoor unit replacement. We recommended monitoring the welded area and scheduling an annual pressure check given the pipe length and property layout.

The leak at the outdoor connections was welded and the system recharged. Concealed piping remained untouched. Cooling returned across all three rooms with no gas loss detected at follow-up.

How nitrogen pressure testing isolates leaks in long pipe runs.

• –Landed properties often have pipe runs extending through walls, ceilings, or outdoor channels. A gas leak could be at any point along the route.
• –Nitrogen pressure testing lets each section be isolated and tested on its own, narrowing the leak location without opening anything.
• –If the outdoor unit connections lose pressure while the concealed section holds, the leak is at the accessible outdoor end.
• –This approach can save significant cost by avoiding unnecessary hacking of walls or ceilings.