Recurring gas loss traced to corroded pipe joint near outdoor unit

What we found

Recurring gas loss that restores cooling temporarily points to a refrigerant leak, not a compressor fault. We pressure-tested the system to locate where the gas was escaping instead of topping up again.

• Compressor was running normally and cooling returned strongly right after each previous top-up — consistent with a leak, not compressor wear
• Pressure test showed a slow pressure drop, confirming a leak in the refrigerant circuit
• Leak was localised to a pipe joint near the outdoor unit — the copper at the joint showed visible green corrosion
• Surrounding environment was heavily shaded with tree canopy overhead and damp leaf litter near the base of the outdoor unit

The outdoor pipe joint had corroded over the years from sustained moisture in the sheltered, wooded location. The tree canopy trapped humidity and prevented the joint from drying between rain. The corrosion gradually opened a slow leak path at the joint. Refrigerant escaped over weeks, and each top-up simply replenished what was leaking out.

What we did

GOOD NEWS — the compressor was not failing. The recurring gas loss was caused by a corroded pipe joint near the outdoor unit. We repaired the joint, confirmed the pressure held, and recharged the system. The leak cycle should now stop. We also recommended clearing vegetation away from the outdoor unit to reduce moisture retention around the joints.

The gas charge held after the joint repair. Cooling has remained consistent without further top-ups. The compressor was retained. The client cleared some of the surrounding vegetation to improve airflow and reduce moisture around the outdoor unit.

What we learned

Why forested and sheltered outdoor locations accelerate pipe corrosion.

• Outdoor pipe joints are exposed to the environment. In open, well-ventilated locations the joints stay relatively dry between rain. In sheltered, heavily shaded spots — near trees, under overhangs, or in enclosed ledges — moisture lingers on the copper surfaces for much longer.
• Sustained moisture on copper pipe joints accelerates corrosion. Over the years the corrosion eats into the joint, creating a slow leak path. The leak is too small to hear or see, but large enough to drain the charge over weeks.
• Each gas top-up without finding the leak just buys time. The refrigerant escapes through the same corroded point. Repairing the joint and then recharging is the only way to stop the cycle.