Freezer has heavy frost buildup on the rear interior panel, leading to reduced airflow and rising temperature.

Safety first: Unplug the freezer before removing any panels or testing components.

• Manual defrost: Remove food, unplug the unit, and allow the ice to melt from the evaporator. Use towels to absorb the water.
• Access the evaporator: Remove the rear interior panel to expose the evaporator coil, heater, and thermostat.
• Test the heater: Disconnect the heater leads and check for continuity. Replace it if open.
• Test the defrost thermostat: With the thermostat cold (in ice water), it should show continuity. Replace it if open when cold.
• Check the defrost control: On mechanical timer models, try advancing the timer into defrost. If it does not energize the heater, replace the timer. On electronic models, if the heater and thermostat are good, replace the main control board.