ARadiator Fan, Temperature Switch is a small and simple switch which is set-up to work based upon the temperature of the engine. There are many other engine systems which are also indirectly affected by the operation of this switch.
The temperature spec is important. Having the fan come on at the right temperature is pretty well the point of having the fan, and with the sensor in the bottom of the radiator it needs to come on at a lower temperature than if it were in the top of the radiator.
Worth getting the right sensor in there before the summer.