I'm wiring up my Derale Dual fans. I have a pair of Painless relays for them as well. I need an ignition switch source, preferably something close to the front of the car/near the radiator. I tried looking at my wiring diagram but can't be sure if the horn relay might work. If someone could please advise.

Thanks.

How are going to control when the fans turn on and off? Are you installing a temperture sensor in the head? Or manual toggle switch? Or are the fans going to run continuously once the vehicle is started? Are you running Air Conditioning also?

The horn relay can be the power feed to the relays to power the fans once the relay is activated, but you will need some type of switch or sensor to tell the relays when to turn the fans on. There's several different ways to wire up the fan relays, once you determine what type of source will control fans on/off cycle.

Don

You should be fine with about any ignition switched 12v source. It's just controlling the relay... not much current draw. The main fan power should come directly from the battery, through a separate 50 amp fuse to the relay using at least a 10AWG wire, or 8AWG would be even better.
-Bill

There is a separate thermostat in the intake manifold to turn on the fans. I have the power leads connected too. However, there are these other two wires that are supposed to be connected to an ignition switch source. I guess this is so the fans only activate when the car is running?

I'd push a wire through a plastic gromment and tie them to the IGN on the fuse block.

Originally posted by John_Muha:
I'd push a wire through a plastic gromment and tie them to the IGN on the fuse block. I was hoping to avoid that because it's getting crowded down there. But if I can't find anywhere else, then that's what I'll do.

Thanks.

I think John's suggestion is best... however, couldn't you tap into the electric choke wire if you have one?

Originally posted by ben70:
I was hoping to avoid that because it's getting crowded down there. But if I can't find anywhere else, then that's what I'll do.

Thanks. What else is tied to that terminal?

Originally posted by John_Muha:
</font><blockquote>quote:</font><hr />Originally posted by ben70:
I was hoping to avoid that because it's getting crowded down there. But if I can't find anywhere else, then that's what I'll do.

Thanks. What else is tied to that terminal? </font>[/QUOTE]I think I have some accessories plugged in down there. I guess I can just add another daisy chain if I need to.

And no, I have no electric choke (no choke at all for that matter).

Thanks.

Don't know what those items are but you may be able to move those items to ACC and avoid the daisy chain.

Originally posted by John_Muha:
Don't know what those items are but you may be able to move those items to ACC and avoid the daisy chain. I'm going from memory since I'm at work and can't take a look at it. I'll stop by later and check it out.

If your thermostat controlling the fans is a one wire type, it will go to ground when it reaches its activation temperture. If thats what you have, here's one way to wire it to activate the fan relays:


http://members.cox.net/hoptup32/FAN.jpg

I'm going to take a look at everything on Saturday. Thanks.

I am using Derale dual fans as well. I currently run them from toggle switches through relays and 30 amp fuses. Use high quality fuse holder, I melted the cheapy parts store fuses. One suggestion I will make is run them to a circuit that is momentarily interrupted when starting the car. If you connect to the fuse box as an accessory I think it will try to operate the fans when trying to start the car when the water temp is hot. You do not want this to happen. If I forget to switch my fans off and try to start the car with the fan switches "on" the battery does not have enough spare current to crank the engine.