were is the fan sensor for the rad fans

hello. i own a 1988 r/r classic 3.5v8 with the flapper system . i am after the sensor that brings the twin rad fans on. is it the one in the houseing that the top hose goes to as it got 2 wires going to it. i found the temperture gauge one with the single wire but found this big one above it.can someone confirm or point me in the right direction thanks,

The twin a/c condenser cooling fans are also switched by the temp sensor in the thermostats housing, but only if there's a likely hood of the engine over heating.

hi thanks i thought that would be the one.as ive done away with the viscous fan and fitted a switch to them via a relay. but i want to fit them to the thermostate switch so they operate from another relay as the wireing has been messed about with.