Er dS
Kenmore Defrost Sensor (Thermistor) Failure

Error code Er dS displayed, unit may short cycle defrost or show inconsistent cooling and frost patterns.

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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 thermistor, Damaged thermistor wiring harness, Poor thermistor mounting on evaporator, Faulty main control board sensor input

How to Fix / Troubleshooting

Safety first: Unplug the refrigerator before testing sensors or removing panels.

Procedure:

  • 1. Access evaporator area: Remove interior rear panel in the freezer or fresh food section (depending on model) to expose the evaporator and attached sensors.
  • 2. Locate defrost thermistor: It is usually a small plastic-encased sensor clipped to the evaporator tubing with two wires leading to a connector.
  • 3. Inspect physically: Check for broken wires, cracked sensor housing, or a loose clip that prevents good contact with the tubing.
  • 4. Test resistance: Disconnect the thermistor from the harness. Measure resistance with a multimeter at a known temperature (e.g., room temperature ~25°C). Typical NTC thermistors read around 5k–10k ohms at room temp (check service data for your model). A reading of 0 ohms (short) or OL (open) indicates failure.
  • 5. Test at cold temperature: Place the sensor tip in a cup of ice water for several minutes and recheck resistance. It should increase significantly compared to room temperature. No change suggests a bad sensor.
  • 6. Replace thermistor: If readings are out of spec, install a new OEM defrost thermistor. Clip it firmly to the same location on the evaporator tubing and route wires away from sharp edges.
  • 7. If thermistor tests good: The main control board may be misreading the sensor. Inspect and, if necessary, replace the board.
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Repair Difficulty

Medium 3/5

Required Part

Defrost Thermistor
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