F3
JennAir Defrost Circuit Sensor / Heater Monitoring Fault

Display shows F3, unit may not enter defrost or may stay in defrost too long.

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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

Defrost sensor not detecting temperature change, Open defrost heater, Control board defrost timing failure, Wiring harness issue in defrost circuit

How to Fix / Troubleshooting

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

  • Step 1 – Inspect evaporator frost pattern: Remove the rear interior panel. If the coil is a solid block of ice, defrost is not working. If completely bare and warm, the unit may be stuck in defrost.
  • Step 2 – Check defrost sensor and heater: Test continuity of the defrost thermistor and heater as described in other defrost-related entries.
  • Step 3 – Examine wiring: Look for broken or burned wires around the heater and sensor.
  • Step 4 – Replace failed components: Replace any open heater or faulty sensor. If both are good, the main control board may need replacement.
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Repair Difficulty

Hard 4/5

Required Part

Defrost Heater
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