Official Sub-Zero bottom-mount refrigerator parts

Common repair parts for Sub-Zero bottom-mount refrigerators

• Condenser fan. 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.
• Defrost bi-metal thermostat. The defrost bi-metal thermostat is a safety device attached to the evaporator coil. The defrost bi-metal thermostat shuts off the refrigerator defrost heater if the heater gets hot enough to damage the evaporator.
• Electronic control board. The refrigerator electronic control board controls the major electro-mechanical components in the refrigerator. When the electronic control board senses the compressor needs to run to cool the refrigerator, it sends voltage to the compressor and fans. It then receives input from temperature sensors to monitor the temperatures inside the refrigerator and freezer sections. With this information, the electronic control board controls the defrost cycle.
• Evaporator fan motor. The evaporator fan motor blows air across the evaporator coils and through the refrigerator cabinet for cooling. Replace the evaporator fan motor if it won't run when activated.

What to do when you see frost buildup in the freezer of your Sub-Zero bottom-mount refrigerator

When frost is building up in the freezer, check first for a break in the door gasket or drawer gasket that could be letting in warm, moist air. If the gasket seems sound, a malfunction somewhere in the automatic defrost system could be the culprit.

A failed defrost timer or a bad electronic control board may not initiate the automatic defrost cycle, causing excessive frost buildup on the back wall inside the freezer. A faulty defrost sensor can prevent the defrost heater from turning on the defrost cycle. See how to check the defrost sensor and other components in the defrost system in our refrigerator won't cool troubleshooting video.