F4
Hitachi
Compressor Discharge Temperature Sensor Fault
Unit stops with F4, compressor may attempt to start then shut down
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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 discharge thermistor, Sensor not properly attached to discharge pipe, Damaged sensor wiring, Faulty outdoor PCB sensor circuit
How to Fix / Troubleshooting
Safety first: Turn OFF power and wait for the compressor and pipes to cool; discharge line can be extremely hot.
Steps:
- Locate sensor: Find the thermistor clamped to the compressor discharge pipe (small diameter hot pipe) near the compressor.
- Check attachment: Ensure the sensor is tightly clamped with metal clip or strap and insulated as originally installed.
- Inspect cable: Look for heat damage or cuts in the sensor wires. Replace if damaged.
- Check connector: Verify the connector is firmly seated on the outdoor PCB.
If F4 persists after sensor replacement: The outdoor PCB may be faulty and should be tested by a technician.
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Repair Difficulty
Hard
4/5
Required Part
Compressor Discharge Temperature Thermistor
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