Refrigerator Has Frost or Ice Buildup

If the refrigerator's defrost drain is clogged, it's possible the evaporator fan motor is not working. If the evaporator fan is not running, cold air from the evaporator can migrate to the defrost drain causing ice buildup in the drain. To determine if the evaporator fan motor is defective, try turning the fan blade by hand. If the fan blade does not turn freely, replace the fan motor. Additionally, if the motor is unusually noisy, replace it. Finally, if the motor does not run at all, use a multimeter to test the motor windings for continuity. If the windings do not have continuity, replace the evaporator fan motor.

Some defrost drains are outfitted with a drain strap. The drain strap is a small piece of copper or aluminum that attaches to the defrost heater and extends partway into the defrost drain. When the defrost heater turns on, heat is conducted through the drain strap to melt away any ice that may have accumulated further down in the defrost drain. If the drain strap is not in place, the defrost drain may be more likely to freeze over.

If the refrigerator's defrost drain is clogged, it's possible the evaporator fan motor is not working. If the evaporator fan is not running, cold air from the evaporator can migrate to the defrost drain causing ice buildup in the drain. To determine if the evaporator fan motor is defective, try turning the fan blade by hand. If the fan blade does not turn freely, replace the fan motor. Additionally, if the motor is unusually noisy, replace it. Finally, if the motor does not run at all, use a multimeter to test the motor windings for continuity. If the windings do not have continuity, replace the evaporator fan motor.

Some refrigerators are equipped with drain heaters. Drain heaters prevent the water in the drain pan from re-freezing and clogging the defrost drain. If your drain heater is defective or is not in the proper position, the defrost drain might freeze over.

One component of the ice maker assembly might be defective. Since many of the ice maker components are not sold separately, you may need to purchase and replace the entire ice maker assembly.

The auger motor spins the auger blade and pushes the ice through the dispenser chute. If the auger motor is burned out or defective, the ice won’t move forward and fall through the chute. To determine if the auger motor is defective, pull out the ice bucket and turn the bucket auger by hand. If the auger turns freely, use a multimeter to test the auger motor for continuity. If the auger motor does not have continuity, or if the motor is getting power but won’t run, replace the auger motor.

The defrost heater assembly turns on several times throughout the day to melt away any frost that may have accumulated on the evaporator coils. If the defrost heater assembly is defective, the defrost system will not work, and frost will continue to accumulate on the evaporator coils. To determine if the defrost heater is defective, use a multimeter to test it for continuity. If the defrost heater does not have continuity, replace it.

The defrost thermostat monitors the temperature of the evaporator coils. When the coils drop below a set temperature, the thermostat contacts close to allow power to flow to the defrost heater during the defrost cycle. In the defrost cycle, the defrost heater melts away any frost that may have accumulated on the evaporator coils. If the defrost thermostat is defective, the thermostat contacts will not close. As a result, the thermostat won’t provide power to the defrost heater. To determine if the defrost thermostat is defective, use a multimeter to test it for continuity. If the defrost thermostat does not have continuity when it reaches the low temperature of its operating range, replace it.

A thermistor monitors the temperature of the evaporator coils. If the coils are below a set temperature, the thermistor will alert the defrost control to allow power to flow to the defrost heater during the defrost cycle. In the defrost cycle, the defrost heater melts away any frost that may have accumulated on the evaporator coils. If the thermistor is defective, the defrost control will not be alerted to allow voltage to be sent to the defrost heater.

The defrost sensor monitors the temperature of the evaporator. The defrost sensor has a fuse to back up the sensor in case the sensor fails. If the defrost sensor fails to shut off the defrost heater, the fuse will blow in order to shut off the defrost heater. If the defrost sensor fuse blows, the defrost system will not work, and the refrigerator will not defrost. The defrost sensor fuse is not resettable—if the defrost sensor fuse blows, you must replace the defrost sensor. To determine if the defrost sensor or fuse is defective, use a multimeter to test both the sensor and fuse for continuity. If either the defrost sensor or fuse does not have continuity, replace the defrost sensor.

The main control board regulates the power supply to all of the refrigerator components, including the defrost system. If the main control board is defective, it may stop sending voltage to the defrost system. Control boards are frequently misdiagnosed—before replacing the main control, first test all of the defrost system components. If none of the defrost system components are defective, consider replacing the main control board.

The control board regulates the power supply to all of the refrigerator components, including the defrost system. If the main control board is defective, it may stop sending voltage to the defrost system. Control boards are frequently misdiagnosed—before replacing the main control, first test all of the defrost system components. If none of the defrost system components are defective, consider replacing the control board.

French door refrigerators will often use a mullion heater flap which flips open as the two main doors are closed to provide a proper seal. If the mullion heater is misaligned or damaged, it can prevent the doors from closing properly. Inspect the mullion heater for any damage and replace it with a new one if necessary.

A refrigerator door support is often used on French Door models to flip a mullion heater flap to seal the gap between the doors. If the door support is damaged or misaligned, the mullion heater flap may not be positioned appropriately for the door or doors to close completely. Inspect the support for damage and replace if necessary.

A door guide is often used on French door refrigerators to assist in flipping open a mullion heater flap to provide a seal between the two main doors. If the guide is damaged or misaligned, the flap may not engage accurately and prevent the doors from closing properly. Inspect the door guide (often attached to the inner liner at the top of the frame) and replace it with a new one if necessary.