E4
Hoshizaki High Discharge Temperature or Discharge Thermistor Error

Digital display shows E4; unit shuts down on safety

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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

Dirty condenser causing high head pressure, Failed condenser fan motor, Faulty discharge thermistor, Refrigerant overcharge or restriction

How to Fix / Troubleshooting

Safety First: Disconnect power before cleaning or testing components. Do not open the sealed system.

  • Clean condenser coil: Thoroughly clean the condenser fins and ensure unobstructed airflow.
  • Check condenser fan: Verify the fan spins freely by hand and runs when the compressor is on. Replace if seized or not running.
  • Inspect discharge thermistor: Locate the sensor on the compressor discharge line. Ensure it is firmly attached and not damaged. Test resistance and compare to spec.
  • Check ambient temperature: Ensure the unit is not installed in a space exceeding the maximum ambient temperature.
  • Reset error: After corrections, clear E4 and monitor operation. If discharge line remains excessively hot, shut down and call a technician.

When to call a technician: Persistent E4 after airflow and sensor checks indicates a sealed system issue that requires professional diagnosis.

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Repair Difficulty

Professional Required 5/5

Required Part

Discharge Line Thermistor
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