Fan on all the time

[11redrex]

I know it's robbing the engine of a few HP and increasing fuel costs, could somoene explain to me how the viscous coupling works please.
Also could it be related to the ECU being "redundant" ?

 

[96terrano]

I copied this little bit of info from here

http://uk.answers.yahoo.com/question/index?qid=20090215034636AAkulmS

When you start your car from cold, you'll get a 'roar' for a couple of hundred yards - this is the viscous fan 'catching up' with the engine speed.
As the temperature gauge rises to about half scale, this roar should return as the viscous coupling forces the fan to turn at the same speed as the water pump (which it's attached to), pulling cold air through the radiator. If the car gets hot & you don't get the noise, I'll 100% guarantee that your viscous coupling has gone. They only have a life of about 60k miles.

Dunno if it's any good at explaining how it works

 

[solarman216]

the viscous fan has nothing to do with anything electrical, it is purely a mechanical device, Rick

 

[11redrex]

Been for a couple of long runs and the fan does go off, eventually. Another little problem I can ignore !