Wire unit (reference 2 image "Temperature sensor connection DMD blocks") of the temperature sensor is disconnected from the Signal backplane.

Plug in the wire unit of the temperature sensor into its socket on the Signal backplane.

Damaged wire unit of the temperature sensor (Reference 2 image "Temperature sensor connection DMD blocks") which measures the temperature of the water cooling block of the red channel.

1. Repair the wire unit.

2. If not repairable, replace the whole wire unit and temperature sensor.

Defect temperature sensor on the water cooling block of the red channel.

Replace the temperature sensor.