H0
Tosot Indoor PCB EEPROM Parameter Error

Display shows H0, unit may not respond to remote commands

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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 EEPROM data on indoor PCB, Voltage surge or brownout, Incorrect replacement PCB without proper programming, Loose EEPROM module (if socketed)

How to Fix / Troubleshooting

Safety first: Turn off the breaker to the indoor unit.

  • Power reset: Leave power off for at least 10 minutes, then restore and test.
  • Inspect PCB: Access the indoor control box and check for a removable EEPROM module. Ensure it is fully seated.
  • Check part numbers: If the PCB was recently replaced, verify it is the correct Tosot board for your model.
  • Replace PCB: If H0 persists, the indoor PCB (with EEPROM) must be replaced or reprogrammed by an authorized service center.
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Repair Difficulty

Hard 4/5

Required Part

Indoor Main Control Board (with EEPROM)
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