Fujitsu
Control Lockup / Microcontroller Hang
Indoor unit displays lights but does not respond to any commands (frozen controls)
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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
Transient power surge, Firmware glitch, Faulty indoor PCB, Stuck button on wired controller
How to Fix / Troubleshooting
Safety first: Turn off power at the breaker before performing a hard reset.
- Power cycle: Turn off the breaker supplying the indoor unit for at least 5–10 minutes to allow capacitors to discharge. Restore power and test.
- Check controller: If using a wired controller, ensure no buttons are physically stuck. Disconnect and reconnect the controller cable.
- Factory reset: Some Fujitsu models support a reset via remote control sequence (refer to the user manual). Perform this if available.
- PCB replacement: If the unit remains unresponsive, the indoor PCB may be defective and should be replaced.
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Repair Difficulty
Medium
3/5
Required Part
Indoor Main PCB
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