Your machine has a separate evaporator for the refrigerator section. The refrigerator and the freezer each have an evaporator and are cooled individually. Make sure the fan at the top of the air tower is working. If the compressor is running and there is no frost on the evaporator coils, the problem could be a refrigerant leak. Many Samsung refrigerators incorporate the Time Divided Multi-cycle (TDM) System to switch refrigerant flow. The TDM design uses a stepper motor and a diverter valve to switch refrigerant flow. Depending on temperature values, the refrigerant can be applied to the full loop or to the freezer section only. Force on the fridge using the “Power Cool” option. Monitor the fridge evaporator temperature
by measuring the voltage at the refrigerator defrost sensor. The temperature at the sensor should decrease, causing the voltage to increase. If the sensor voltage is not changing, suspect that the main PCB is defective and not supplying the signal to switch the diverter valve to the full position. Look on your tech sheet for the defrost sensor connector on the main board.