Samsung Air Conditioner Error Code P515

The P515 error code on a Samsung air conditioner indicates that the outdoor unit has activated SUMP DOWN protection control at its third threshold level. This is a compressor sump protection function designed to prevent the compressor from operating under conditions where liquid refrigerant has migrated to the compressor sump (bottom of the compressor housing). When liquid refrigerant accumulates in the compressor oil sump, it dilutes the lubricating oil and creates a risk of liquid slugging, which can cause severe mechanical damage to the compressor internals. The "3" designation in the code name indicates this is the third and typically most critical stage of this protection sequence.

The protection is triggered when the unit's control logic detects conditions consistent with refrigerant flooding in the sump area, which is often inferred through temperature sensors monitoring the compressor body or discharge line. Common contributing factors include extended periods of unit inactivity during cold ambient temperatures, refrigerant overcharge, loss of crankcase heat function, or a failed compressor heater that would otherwise prevent refrigerant migration during off cycles. The outdoor PCB monitors these conditions and engages the protection to prevent compressor startup until conditions are safe.

When P515 is active, the system will restrict or halt compressor operation to allow the refrigerant to boil off from the sump oil before restarting. In some cases the unit will attempt a controlled warm-up sequence. If the error persists beyond this warm-up period, a fault in the compressor temperature sensor, the outdoor control board, or an actual refrigerant system issue such as overcharge or a failed crankcase heater is likely responsible.