Samsung Air Conditioner Error Code P512

Error code P512 on a Samsung air conditioner indicates that the compressor has been shut down due to low pressure sensor protection control, specifically identified as protection event 3. This is a refrigerant-circuit-level safety shutdown. The low pressure sensor monitors suction-side pressure in the refrigerant loop. When that pressure drops below the threshold defined for protection level 3, the system controller commands the compressor offline to prevent mechanical damage such as compressor slugging, oil loss, or overheating from running in a low-refrigerant or restricted-flow condition.

Protection control 3 suggests this is a third-tier or third-occurrence protective response within Samsung's low pressure monitoring logic, which may involve repeated detection events or a pressure reading that has fallen into a critically low range. Common triggers include insufficient refrigerant charge due to leaks, a blocked or restricted metering device such as an expansion valve, a dirty or obstructed evaporator coil restricting airflow, or a faulty low pressure sensor reporting inaccurate readings. In split and multi-split systems, a kinked or partially closed service valve can also produce this fault.

Because the compressor is actively protected from running under unsafe pressure conditions, the unit will not resume normal operation until the underlying pressure issue is resolved. Technicians should connect manifold gauges to measure actual suction pressure, verify refrigerant charge levels, inspect the expansion valve operation, and confirm sensor output before attempting a restart. Simply resetting the unit without addressing root cause will typically result in the fault returning.