The 6 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 # 1204741
If the refrigerator is not cold enough, the evaporator fan motor might have failed. Every refrigerator has a set of coils called an evaporator. The refrigerator may have one or more evaporator fan motor(s) depending on the model and evaporator locations. The evaporator fan motor circulates the cold air from the coils thru the compartment. If there is only one evaporator it is in the freezer side. If the fan is not working, no cold air will get to the refrigerator compartment. The freezer may still get cold.
RepairClinic Item # 1703662
If the refrigerator is not cold enough there might be something caught in the condenser fan motor blade, or the condenser fan motor might be defective. The condenser fan motor draws air over the condenser coils to cool them. The condenser fan motor is located underneath the refrigerator near the back. Pull the refrigerator out from the wall and remove the access panel to access it.
RepairClinic Item # 1057227
If the refrigerator is not cold enough the thermistor might be defective. The thermistor is a sensor which monitors the air temperature. It is connected to the control board. If the thermistor is defective the refrigerator does not cool or may cool continuously.
RepairClinic Item # 1876188
If the refrigerator is not cold enough, the compressor might be defective. The compressor is a motor which compresses the refrigerant and circulates the refrigerant through the evaporator and condenser coils. There are several other components which are more likely to be defective if the compressor doesn't work. If the compressor itself is defective a licensed professional will need to replace it.
RepairClinic Item # 1206507
If the refrigerator is not cold enough the main control board might be defective. This is not common. Check the defrost system, cooling fans, and cooling controls first.