Fan Switch

scottyb

Spongebob Squarecar
Joined
Oct 12, 2001
I have wired a high-speed fan switch the way Red Armstrong described. It lets me turn the fan on high, but only when the ignition is on. I also want to switch under the hood the turn it on high when the ignition is off. What's the easiest way?
 
Scotty,

See
http://www.gnttype.org/techarea/images/wiring_images/cooling_fan_circuit.jpg

for a diagram of the fan wiring. The easiest thing would probably be to just make an alligator clip jumper that you hook to the alternator and to the fan motor. If you're determined to do it with a switch and you want the switch to remain low amperage (i.e. activate the existing relay) you need to wire a switch between constant power and the power side of the high speed fan relay coil (brown wire). This will give the high speed relay constant power and your existing switch will then turn the fan on and off.
 
scottyb,

If you ground a wire to the "coolant fan temperature switch"....Dk Green w/ Yellow stripe the fan will run with the ignition off. The fan delay relay will determine how long it runs....mine will run for about 12 minutes after I flip the switch.

If your fan relays are all OK, this is how it is "supposed" to work.

The coolant fan temp switch is the sensor on the intake manifold. If this switch gets too hot (I think around 215) the sensor will act like a ground and the fan delay relay will turn on the fan. This is what happens on a hot day when your fan turns on after you turned off the car.

By tapping into this wire...running it to one side of the switch...and grounding the other side of the switch you "trick" the relay into thinking that the sensor is too hot and the fan will turn on.

Hopefully that all made sense.

Good Luck,
John
 
Top