The 2 most common part(s) or condition(s) which cause the symptom Refrigerator not cold enough are listed below starting with the most likely. Check or test each item and watch any available videos.
If the refrigerator is not cold enough the condenser coils may be dirty. The condenser is like a radiator and must stay clean in order to dissipate the heat which was removed from the inside of the refrigerator. As the coils get dirtier the refrigerator becomes less efficient, which makes it work harder to cool down. If the coils are dirty enough, the unit will never be cold enough and will not be able to cool the inside of the refrigerator to the proper temperature.
RepairClinic Item # 879147
If the refrigerator does not get cold enough the temperature control thermostat might be defective. The thermostat allows power to flow through to the compressor, evaporator fan and condenser fan. If the cooling system fans and compressor are running, but the refrigerator or freezer is not cooling correctly check for an airflow or defrost system problem.