I am installing a E fan in my 99 f150 and have a quick question. The directions say to install one wire to the battery and another to a switched 12v source. Can't you just hook the 2 together ? it not where do I connect for a 12v switched source.
thanks

 

I think your probably dealing with the relay.

You can think of the relay as an electronic switch. The switch is normally off so you hook the one wire to the battery and another goes to the fan. When the relay is told to it then closes this switch and the fan comes on. The wire that goes to the switched power is what triggers the relay to close and the fan to turn on. Now I'm not sure if the fan should be on when the engine is on or just turn on say when the thermostat opens. If you want the fan to run when the engine is on then you have to find a power source that turns on when the engine is started. I have heard that there are places in the under hood fuse box you can hook up to. The place that I use is the wire from my cd player that is used for either an electric antennae or an amp. A relay does not pull much current so you shouldnt have to worry about blowing a fuse or anything but make sure the circuit you hook into has a fuse or your asking for trouble. If you want the fan to turn on just when the engine gets to a certain temp (like when the thermostat opens) I cant help on that one. Hopefully this helps some... Good luck!

 

Probably the easiest way would be to route the wire to the post on the side of the power distribution (fuse) box. It should be under a cover on the side facing the windshield. The post is only hot when the ignition is on.

Hope this helps.

 

You CAN connect the two together, but it would allow the fan to run any time at all.

Here's a pic of a place to get easy underhood access to what you need:



Good luck !!!