حلقات O متهالكة في وصلات النظام

The O-rings sealing the air conditioning system's joints, hardened with age so they no longer seal. Every joint in the system has one, and they are a rubber part in a pressurised circuit — so this is a wear-out failure and the commonest source of slow leaks.

A slow leak gives a system that cools well for a season and poorly the next, which owners describe as gradually getting worse. The leak is usually invisible — refrigerant escapes as gas — so dye or an electronic detector is the only way to locate it. O-rings are single-use and must match the refrigerant, since the material differs between systems; fitting the wrong compound produces a joint that leaks immediately or swells and fails later.