Bass

so i went to the bone yard today to pick up a harness for the electric fan on the la baron - tested it out by adding 12v & a ground directly to the battery and low and behold the fan works (a little loud but works fine)

the game plan is to have the 12v to the fan sitting on a switch inside the car so if it gets hot i just flip the switch BUT i want to make sure when the key is off the fan is off just in case i forget to shut it off

i found this

http://www.r1200gs.info/howto/relay.html

so why do i need a constant 12v to the relay & 12v constant to the switch all the time

and can you buy relays at any auto parts stores

boltonblue

ok first lets think of this as two circuits.

circuit one.
think of the relay as a remote high power switch.
on one side of the high power switch you have battery and fuse and on the other side is your fan. that's one 12V source

circuit two
the high power switch gets closed when you apply power to it. this is the other 12V source. the other side of the switch goes to ground. this 12v source comes from your dash board switch or ignition.
this doesn't draw much power.

and yes you can usually get relays at a parts store, probably a good idea to get the matching connector while your at it.

Cubs2k

http://www.bcae1.com/

#36


Get an automotive 12V relay,

Connect terminal #85 to 12V power with a switch inbetween.
COnnect #86 to a ground
COnnect #30 high power to 12V
Connect #87 to Positive lead of Fan
Ground Neg of Fan

In Jerry's Example
#1 is #30 and 87
#2 is 85/86

Bass

awesome thanks!