H04 error, compressor stops frequently and freezer cannot reach low temperature

Safety: Unplug the freezer. Sharp evaporator fins can cut skin; wear gloves.

Steps:

• 1. Access evaporator: Remove baskets and the inner rear panel of the freezer to expose the evaporator coil and sensor.
• 2. Locate sensor: The Panasonic evaporator thermistor is usually clipped to the evaporator tubing or mounted in a small well on the coil.
• 3. Inspect for ice and damage: Check if the sensor is encased in ice or has broken insulation. Look for pulled or broken wires where they exit the liner.
• 4. Thaw if necessary: If heavily iced, allow the unit to defrost fully (doors open, towels on floor) before testing. Do not chip ice with sharp tools.
• 5. Test sensor: Disconnect the sensor and measure resistance at known temperatures (e.g., in ice water). A reading far outside Panasonic specifications or open/short indicates failure.
• 6. Replace sensor: Install a new Panasonic evaporator thermistor, clipping it firmly to the same tube and routing wires away from heater elements.
• 7. If sensor is OK: The main control PCB may be misreading the sensor; professional diagnosis is recommended.