Ok stupid question but what is the fan clutch? Where is it and what does it do?

 

The fan clutch is on the fan its lets it stop spining when the motor doesnt need the fan.If you try to spin the fan you'll notice it spins freely but out of nowhere when its running it locks up and starts spinning.Once in a while they will wear out and the fan will stay on all the time.Thats why they have the warning label (fan may turn on at anytime)

 

ok cool thanks.

 

That would be the label on an electric fan, which do not have clutches.

The fan clutch is the finned aluminum thingy between your radiator fan and water pump.
When working properly it varies the amount of torque applied from the water pump shaft to the fan itself, the warmer it is the more torque it applies (spins the fan faster) .
Usually when they go bad they dont transmit enough torque (fan spins slow) and engine runs hot especially if you are in stop and go traffic.

The best thing to do if your fan clutch goes bad is remove the fan and clutch and install an electric fan.

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