H4
Hisense
Indoor-Outdoor Communication Timeout / EEPROM Error (model-dependent)
Indoor unit displays H4 and the unit may not start or may stop after a short run.
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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
Corrupted control software, Faulty indoor or outdoor PCB memory, Electrical noise or surges, Loose communication wiring
How to Fix / Troubleshooting
Safety first: Disconnect power before accessing control boards.
- Step 1 – Power cycle:
- Turn off the breaker for 10–15 minutes to fully discharge capacitors and reset the control.
- Step 2 – Check wiring:
- Inspect the communication cable between indoor and outdoor units for damage and tight connections.
- Step 3 – Surge protection:
- If your area has unstable power, consider installing a surge protector (by an electrician) to protect the electronics.
- Step 4 – Technician repair: Persistent H4 usually requires PCB replacement or reprogramming by an authorized Hisense service center.
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Repair Difficulty
Professional Required
5/5
Required Part
Indoor Main Control Board (PCB)
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