I'm having a little trouble understanding what these sensors do and which one(s) affect fan operation. I see the image below all over the site so it'd probably be a good reference. Here are my guesses but if anyone knows better than me please fill in the blanks. The wires to all of these sensors have broken off on my car, and the radiator fans don't work. I'm mainly trying to figure out what sensor turn the fans on, but it'd be nice to know what each of these does.
1. Engine Coolant Temp Gauge Unit -
Sends a signal to the temp gauge in the dash
2. Engine Coolant Temp Sensor -
Sends temp signal to the ECU?
3. Air Conditioning Engine Coolant Temp Switch -
Disables AC if the temp gets too hot?
4. Engine Coolant Temp Switch
Main temp switch that turns fans on?
1. Engine Coolant Temp Gauge Unit -
Sends a signal to the temp gauge in the dash
2. Engine Coolant Temp Sensor -
Sends temp signal to the ECU?
3. Air Conditioning Engine Coolant Temp Switch -
Disables AC if the temp gets too hot?
4. Engine Coolant Temp Switch
Main temp switch that turns fans on?