F1
Mitsubishi Electric
Indoor Humidity Sensor Out of Range
Humidifier/dehumidifier hybrid unit shows F1 and stops; humidity control unavailable.
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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
Humidity sensor contamination by dust or chemicals, sensor element aged or failed, wiring harness damage, main PCB A/D converter fault
How to Fix / Troubleshooting
Safety: Unplug the appliance before opening the front panel.
Steps:
- Access sensor: Remove the front grille or control panel to locate the humidity sensor module (small PCB with vent holes).
- Clean: Use dry compressed air or a soft brush to remove dust. Do not use water or solvents on the sensor.
- Check wiring: Ensure the sensor connector is fully seated on both the sensor PCB and main PCB. Inspect for broken conductors.
- Test operation: Reassemble, power on, and see if F1 clears. If not, the sensor is likely defective.
- Replace: Install a new humidity sensor assembly. If the fault persists, the main control PCB may need replacement.
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Repair Difficulty
Medium
3/5
Required Part
Humidity Sensor Assembly
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