H4
Sharp
Indoor–Outdoor Mismatch or Configuration Error
Unit does not start; H4 displayed immediately after power-on.
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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
Incorrect indoor unit model paired with outdoor unit, Wrong DIP switch or jumper settings on PCB, Corrupted configuration data on PCB
How to Fix / Troubleshooting
Safety first: Turn off power before opening any control boxes.
- Verify model compatibility: Check that the indoor and outdoor model numbers are designed to work together according to Sharp documentation.
- Check PCB settings: Some Sharp systems use DIP switches or jumpers to set capacity or mode. Compare settings to the installation manual and correct if wrong.
- Reset configuration: Perform a full power reset. On some models, a service reset procedure (button sequence) may be required; refer to the service manual.
- PCB replacement: If configuration cannot be corrected or is corrupted, the relevant PCB may need replacement and configuration by a Sharp technician.
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Repair Difficulty
Hard
4/5
Required Part
Indoor Main Control PCB
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