F04
Hotpoint-Ariston Defrost Sensor / Thermostat Error

Error F04; freezer may not defrost and frost accumulates on the evaporator cover.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Open or shorted defrost thermostat, Defective evaporator NTC sensor, Wiring fault between sensor and control board

How to Fix / Troubleshooting

Safety first: Unplug the freezer before working near the evaporator or heater.

  • Manual defrost: Unplug and fully defrost the unit to restore airflow temporarily and confirm a defrost system issue.
  • Locate defrost thermostat: It is usually clipped to the evaporator tubing. Inspect for cracks or signs of overheating.
  • Continuity test: With a multimeter, test the thermostat for continuity when cold (should be closed). If open when cold, replace it.
  • Check NTC sensor: If your model uses an NTC instead of a mechanical thermostat, test its resistance and replace if out of spec.
  • Replace faulty component: Install the correct Hotpoint-Ariston defrost thermostat or sensor and secure it firmly to the evaporator.
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Repair Difficulty

Hard 4/5

Required Part

Defrost Thermostat
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