Where do mini splits usually leak refrigerant?

Refrigerant leaks in a ductless mini-split system typically occur most frequently at the mechanical flare connection fittings where the copper refrigerant lines attach to the service valves on the outdoor condenser unit or the back of the indoor air handler. Because these flare joints rely on precise metal-to-metal seating tightened by hand or wrench during installation, minor imperfections, vibration, or temperature expansion cycles can create microscopic gaps over time, allowing pressurized gas to escape. Other potential leak points include rusted copper line sets, cracked brazed joints, or internal evaporator and condenser coil pinholes. You can troubleshoot by inspecting flare connections for oily residue or using electronic leak detectors. You can verify that the leak location is identified when professional pressure testing or UV dye testing confirms the exact rupture point requiring repair.