F6
Tosot
Compressor Low Frequency Protection / Inverter Drive Fault
Indoor unit displays F6, compressor may not start or may shut down quickly
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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
Inverter PCB unable to drive compressor at low frequency, DC bus voltage instability, Compressor mechanical issue at low speed, Faulty current sensor on outdoor PCB
How to Fix / Troubleshooting
Safety first: Only qualified personnel should work inside the outdoor control box. Disconnect power and wait for DC bus capacitors to discharge.
- Visual inspection: Open the outdoor control box and inspect the inverter PCB for burnt components, bulging capacitors, or discoloration.
- Check wiring to compressor: Ensure all compressor terminals and harnesses are tight and undamaged.
- Power reset: Restore power after 10 minutes and test operation. If F6 reappears, the inverter PCB or compressor may be faulty.
- Professional diagnosis: A technician should measure DC bus voltage, compressor winding resistance, and insulation. Replace the inverter PCB or compressor as indicated.
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Repair Difficulty
Professional Required
5/5
Required Part
Outdoor Inverter Control Board
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