Samsung Air Conditioner Error Code Bx

The Bx error code on a Samsung multi-zone air conditioning system indicates that the evaporator outlet (EVAP OUT) temperature sensor on the xth indoor unit has become disconnected or has lost proper contact with its mounting point. The "x" in the code corresponds to the address number of the specific indoor unit within the system, so B1 refers to indoor unit 1, B2 to indoor unit 2, and so on. This sensor is a thermistor mounted at the outlet side of the indoor unit's evaporator coil, and it provides real-time refrigerant temperature data to the system controller. That data is essential for accurate capacity control and protection against coil icing or refrigerant flooding.

The primary cause of this fault is physical breakaway of the sensor from its clip or mounting bracket rather than an electrical failure of the sensor itself. When the sensor loses contact with the coil, it no longer reads coil temperature accurately. It instead reads ambient air temperature inside the unit casing, causing the controller to detect an abnormal or inconsistent temperature signal and trigger the fault. The system halts normal operation on the affected indoor unit to prevent potential damage from uncontrolled refrigerant conditions.

Diagnosis should begin with a physical inspection of the EVAP OUT sensor on the identified indoor unit. The technician should remove the indoor unit cover, locate the evaporator coil outlet sensor, and verify it is firmly seated in its clip and making direct contact with the coil fins or pipe. Reassembling the sensor to its correct position and resecuring the mounting clip is typically sufficient to resolve the fault. If the sensor remains loose or the clip is damaged, replacement of the sensor or its retaining hardware is required.