H3
Fujitsu
Compressor Lock or Start Failure Protection
Indoor unit shows H3, compressor does not start
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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
Locked rotor compressor, Severe refrigerant imbalance, Inverter module failure, High supply voltage fluctuation
How to Fix / Troubleshooting
Safety first: This involves high-voltage and refrigerant components. Only qualified technicians should perform detailed diagnostics. Disconnect power at the outdoor disconnect.
- Homeowner checks:
- Ensure supply voltage is stable and within the range specified on the outdoor unit nameplate.
- Verify outdoor fan runs when the unit attempts to start.
- Technician diagnostics:
- Measure compressor winding resistance and check for mechanical lock.
- Verify inverter output and DC bus voltage.
- Check refrigerant pressures for signs of severe overcharge or blockage.
- Repairs: Replace the compressor if locked or shorted. If compressor is good, replace the inverter PCB. These repairs require specialized tools and should not be DIY.
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Repair Difficulty
Professional Required
5/5
Required Part
Compressor (Inverter Type)
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