Refrigerator: Why is my freezer not cold enough?

The refrigerator defrost sensor-also known as the defrost bi-metal termination thermostat-trips when it detects that the temperature of the evaporator is getting hot enough that it might overheat. When the defrost sensor trips, it shut off power to the defrost heater. If the defrost sensor trips because it's not working correctly, frost builds up on the evaporator fins, eventually making the refrigerator and freezer not cool well. You can use volt/ohm meter to check the defrost sensor for continuity. Replace the defrost sensor if it shows no continuity at around 0 degrees F.

Dust-covered refrigerator coils can prevent the refrigerator and freezer from running efficiently and cooling properly. Follow the instructions in your owner's manual for cleaning the condenser coils. Unplug the refrigerator before accessing and cleaning the coils. On most refrigerators, the coils are behind the bottom front grill. Clean the condenser coils with a coil brush.

The condenser fan is in the machine compartment of the refrigerator next to the compressor. It moves air across the condenser coils to help cool the hot refrigerant coming out of the compressor. The refrigerant is cooled before it moves through the expansion device and into the evaporator. If the condenser fan is defective, replace it.

The refrigerator automatic defrost system periodically melts frost from the evaporator to improve heat exchange. During defrosting, the compressor stops, the defrost heating element turns on, and frost melts from the evaporator fins. The condensate drips to a evaporator drip tray below the evaporator and then flows through a defrost drain tube to a drain pan next to the compressor in the machine compartment. The condensate water evaporates from the drain pan before the next defrost cycled. If the defrost process fails, diagnose and repair the problem.

The evaporator fan is mounted on the evaporator assembly. It moves air across the evaporator fins and through the cabinet for cooling. If the evaporator fan is defective, replace it.

The temperature control board-also called the electronic control board-is in the machine compartment next to the compressor, behind a panel on the back of the refrigerator. The temperature control board controls the compressor and other major components in the refrigerator. You can test it using the diagnostic test procedures provided in the tech sheet for the refrigerator. Replace the temperature control board if it doesn't work at all or isn't controlling the components correctly.

The temperature control thermostat is also called the cold control or cold control thermostat, and is located in the control housing. The thermostat has a sensor tube attached to it that detects the temperature inside the refrigerator cabinet. The temperature control thermostat controls the temperature inside the cabinet by turning on and shutting off the compressor based on the temperature sensed by the sensor tube. Replace the temperature control thermostat if it fails to sense temperature properly or if it does not cycle the compressor properly.

If the refrigerator is not cooling enough, the thermistor might be faulty. The thermistor sends temperature information to the thermostat, so a broken thermistor will give bad information.

The defrost timer is an electro-mechanical device that controls the intervals between automatic defrost cycles in the refrigerator. The defrost timer motor runs and moves the control components in the device. When the control contacts in the defrost timer advance into the defrost cycle, the compressor stops and the defrost heater turns on for a specified period of time to melt frost off of the evaporator fins. This promotes more efficient exchange of heat across the evaporator. When the specified period of defrost ends, the defrost timer contacts switch back to allow normal cooling operation in the refrigerator.

You'll need to replace the defrost timer if it doesn't advance when activated.

Faulty contacts in the timer can also cause the defrost heater to either not energize at all or constantly energize. In that instance, replace the defrost timer.

The refrigerator or freezer doors swing on hinges that can be damaged or bent. Over time, the doors may begin to sag, allowing warm moist air into the refrigerator or freezer door that creates excessive frost that can eventually cause the drain tube to freeze. This refrigerator repair involves adjusting or repairing the hinges so that the doors work properly and stay aligned.

The door gasket attaches to the refrigerator or freezer door panel and prevents air from entering or escaping the cabinet when the door is shut. A damaged gasket lets warm, moist air into the refrigerator when the door is closed, causing excessive frost and cooling problems. Replace the door seal if it's damaged or torn.

The electronic control board-also called the main control board or the power control board (PCB)-controls the compressor and the defrost cycle. When it senses that the compressor must run to keep the refrigerator cool, it sends voltage to the compressor and fans. The electronic control board also receives signals from temperature sensors to monitor the temperatures inside the refrigerator and freezer. With this information, the electronic control board controls the defrost cycle. You can usually do a diagnostic test on the electronic control board to see how well it's working. The test varies by model, but the most common is the Forced Defrost test. See the tech sheet for instructions on running the diagnostics. Replace the electronic control board if it's not working correctly.

Dust-covered refrigerator coils can prevent the refrigerator and freezer from running efficiently and cooling properly. Follow the instructions in your owner's manual for cleaning the condenser coils. Unplug the refrigerator before accessing and cleaning the coils. On most refrigerators, the coils are behind the bottom front grill. Clean the condenser coils with a coil brush. Additional routine maintenance includes replacing the water filter, cleaning the dust from the bottom front grille, adjusting the hinges if the doors don't seal tightly, and emptying water from the drain pan.