I think the one pole sensor is for the electronic diesel control, which probably changes fueling based on temperature. Without further research, this one is probably ok.

The two pole switch is a thermistor which senses water temperature for the climate control head unit, which in turn, controls the fans. It's most likely that this sensor is defective. If replacing it doesn't solve the problem, then the CC unit itself may be the problem.

But what is the cause for running so hot? The primary fan is sufficient in most circumstances.