[TR] Fan Hookup

[Dave1massey at cs.com]

In a message dated 11/11/2007 5:20:13 PM Central Standard Time, 
david.brister at wanadoo.fr writes: 
> Is there a guru with a definitive answer to whether it's better to have an 
> electric fan wired to run whenever the thermal switch says so?
> ISTR that I've owned a Volvo and a VW, both of which had fans that would run 
> 
> with engine off and ignition key out, so there must be an argument for 
> this..
> 
Sure.  You can save a $5.00 relay that way.  (actually, the cost to the car 
manufacturer for that relay is under $2.00)  Since fans pull a healthy current 
you don't want it powered off the keyswitch so switching it off with the 
switch requires a relay.

Is there a functional benefit?  No.  As Jim pointed out the engine is off and 
the waterpump is stopped so there is no movement of coolant through the 
radiator.  Also, since the engine is off there is no more heat being produced so 
there is no more need to run the fan.

Dave