I need some help. It's been pretty cold out here latley and when I start my 2000 ES there should be no reason for my radiator fan to come on instantly but it is. Where is the temp sensor the fan uses? Could that be bad? Or does the signal for the fan to come on come from my ECU?

 

is the the climate controll on the window defrost? Because if it is it engages the ac and with the ac on the fan will be on too.