Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

My Diesel Corsa is overheating. The problem is not the coolant, there's no leak and the water pump works.
The fan is not broken so I have narrowed it down (with this site) to probably the water temperature sensor.
The problem I have is that I have no idea where this is or even if it is the correct thing. (I've read there are two of this type of thing, one for the dash and the other for turning the fan on).

To sum up the fan is not coming on but is functioning if I put 12V directly through it. I don't really know what is wrong with it and even if I did I can't find the water temperature sensor (the one on the engine).

Thanks in advance.

you could run the fan off a switch and have the switch on the dash? that would limit the amount of problems you could have in the future with the sensors?