Follow the following instructions to replace the TCU:
1) Shut off the power supply for voltage regulator of the air-conditioner.
2) Shut off the power supply for the TCU.
3) Unclench the screws fastening the TCU, then remove the TCU and place it on the anti-static foam block.
4) Insert a new TCU and fasten it with screws.
5) Start the power supply for voltage regulator of the air-conditioner.
6) Enable the power supply for the TCU.