F9
TCL
Indoor Humidity / Additional Sensor Fault (model-dependent)
Unit shows F9 and may not control temperature correctly
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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
Failed auxiliary sensor (e.g., humidity or secondary temperature sensor), Loose sensor connector, Damaged sensor harness, Indoor PCB sensor circuit failure
How to Fix / Troubleshooting
Safety first: Disconnect power before opening the indoor unit.
- Step 1 – Identify auxiliary sensor: Consult the TCL service manual for your model to locate the F9-related sensor (often near the air intake or PCB).
- Step 2 – Check connection: Ensure the sensor is properly plugged into the PCB.
- Step 3 – Inspect wiring: Look for damage or corrosion on the sensor wires.
- Step 4 – Replace sensor: Install a new OEM sensor if the original is faulty.
- Step 5 – PCB replacement: If F9 persists, the indoor PCB may need replacement.
Warning: Use the exact replacement sensor specified for your TCL model to maintain correct control logic.
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Repair Difficulty
Medium
3/5
Required Part
Indoor Auxiliary Sensor
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