So i recently bought a CJ and there was a hack working on it before me. The elctric fan is a dual fan system but the electrical is not hooked up. Other than the water crossinfg on/off switch would it be a bad idea to just run a little 40 amp fuse block to a switched power source and let the fan run all the time?

Thats how i run my taurus fan. Let the engine warm up then flip it on low. Been working fine for a year.

If your asking, whether or not it will work, the answer is "yes" provided the relay doesnt burn up because its too small.

Wally

When i say switched i mean ignition switched. I don't want to have to bother turning it on or off or making sure my wife turns it on and off.

u hafta run a big relay to an electric fan, it pulls mega juice. no less than 75a. no fuse will stand up to the start up draw of my taurus fan, i found that the hard way. cost almost 90 bux to wire mine in the proper way, but no trouble for 2 yrs now. google taurus fan in yj and read up. your ignition switch idea is fine, but it should be turning on the relay which in turn starts the fan. mine runs constant when ignition is on with no problems, unless the switch i put in is off.

Yes, you can wire your fans that way and it will work reliably IF you have a large enough relay. 40 amps may not be enough. Need to know what size the fan motors are?

You will want to put an appropriate sized thermobreaker or a fuse on the positive side between the battery and the relay.

IMO a slick way to "set it and forget it" is to use an electric fan switch assembly. For $30sh it comes with an adjustable rheostat (thermostat), a 40 amp relay and a 30 amp switch, tie into the ignition siwtch at the starter solenoid. They are sold at just about every autoparts store ie NAPA, Autozone, Parts America.

I went this route with V6 Ford Contour fans, only I had to wire two switches in paralell, one for each fan, because the amp draw on spool up is 70sh or so amps. I can adjust each fan to come on sequentially. I think I got mine at Parts America for $35 a piece with tax. I don't have an in dash manual switch, but I could put one in, and splice it in before the ignition switch at the solenoid.

http://i65.photobucket.com/albums/h224/WallyP226/006-9.jpg

http://i65.photobucket.com/albums/h224/WallyP226/007-10.jpg

Wally

Good answers, thank you.