Freezer has heavy frost buildup on rear interior panel; airflow reduced, temperature rising

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

• Manual defrost: Remove food, unplug the unit, and allow ice to melt from the evaporator. Use towels to absorb water.
• Access evaporator: Remove the rear interior panel to expose the evaporator coil, heater, and thermostat.
• Test heater: Disconnect heater leads and check for continuity. Replace if open.
• Test defrost thermostat: With the thermostat cold (in ice water), it should show continuity. Replace if open when cold.
• Check 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 heater and thermostat are good, replace the main control board.