Refrigerator not cooling in fresh food section but freezer is cold; frost buildup on back freezer wall.

Safety: Unplug the refrigerator before removing panels or testing components. Water from melting ice can create slip and shock hazards; protect the floor and keep connections dry.

Steps to diagnose and correct defrost failure:

• Confirm symptoms: Check for a thick sheet of ice on the freezer back wall and weak or no airflow into the fresh food section.
• Manual defrost: Empty the freezer and remove the rear interior panel. Use a hair dryer on low or leave the unit unplugged with doors open until all ice on the evaporator melts.
• Test defrost heater: Disconnect heater leads and measure resistance. Replace the heater if it reads open (OL).
• Check defrost thermostat: While the thermostat is cold (below freezing), it should read closed (near 0 Ω). Replace if it remains open when cold.
• Inspect evaporator thermistor: Verify it is properly clipped to the evaporator and test resistance at room temperature. Replace if out of spec.
• Control board or timer: If all components test good, the defrost timer (on mechanical models) or main control board (on electronic models) may not be initiating defrost. Replace the faulty control component.
• Reassemble and monitor: After repairs, reassemble panels, restore power, and monitor for normal frost pattern and airflow.