We strip a sample of every compressor returned under warranty. The pattern barely changes from year to year: the compressor is rarely the root cause, it is the component that shows the damage first.
Oil starvation
By far the most common. Either the system was charged without balancing the oil, or a slow leak took oil out with the refrigerant over a season. The bearing surfaces score, the unit gets noisy, and eventually the swash plate picks up.
Debris ingestion
Aluminium glitter in the suction port means an earlier failure was never flushed out. This is why we insist on a new drier, a new expansion device and, on parallel flow systems, a new condenser.
Clutch overheating
An excessive air gap makes the clutch slip, and slip generates heat that cooks the coil. Check the gap against specification before assuming the coil was faulty.
Liquid slugging
Refrigerant that condenses in the compressor while the vehicle stands, then gets compressed on start-up. It bends valve plates. Turning the clutch by hand before first start avoids it.
Control valve faults
On variable displacement units, a valve stuck at minimum stroke looks exactly like a worn compressor from the driver's seat. Test the valve before ordering a whole compressor; it is a fraction of the cost.