Start Relay
If the refrigerator is not cold enough, the start relay may be defective. The start relay is a small device mounted to the side of the compressor. It provides power to the run winding along with the start winding for a split second at start-up to help get the compressor started. If the start relay is defective the compressor may run intermittently or not at all and the refrigerator will not get cold enough. The start relay should be replaced if defective.
Temperature Control Thermostat
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.
Start Capacitor
If the refrigerator isn't cold enough the compressor might be having difficulty starting. The start capacitor serves as a battery to give the compressor a little boost during start-up. If the start capacitor is burned out the compressor might not be able to start and run as often as it should. Test the start capacitor first with a capacitance meter, they don't fail often. If it's defective, replace it.
Thermistor
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.
Temperature Control Board
If the refrigerator is not cold enough the temperature control board might be defective. The temperature control board provides the voltage to the fan motors and compressor. These boards are often misdiagnosed. Check all other components to be certain this is the cause of the problem.