Thermo fans ? Wiring

[fy469rtse]

I've installed two 10" fans in front of condesor and radiator,
For straight air flow on hot days in traffic , stops etc,
The way I'm wiring them in is with relays triggered by Ign source so fans don't run on after car is shut off,
Adjustable temp on using derale units with probes, fused as well,
My question is from all the way from front of vehicle, ?  where or what's an except able Ign on source in engine bay ,
Or do I have to run to inside of dash to pick up source from fuse box or ignition switch,
WHo's done something similar and what did you do,
Have wired adjustable probes and fans to direct power source , fused and curcuit breakers relayed to go live only with ignition on , but ignition source, to trigger relays ?
No spare wire points left in bulk head ?

[Dino]

You actually could give the relay constant power so the fans keep spinning for a bit after you turn the ignition off.  Since it's a thermostatic switch it should not run when the car is off so it won't start up unless you pass that point where the switch kicks in.

If you do want keyed then you can tap it straight from the ballast resistor, brown wire I think.  You can also tap it straight from the bulkhead connector for a cleaner look. 

You could install the whole thing and do the wire last just to see what the best spot would be.

[John_Kunkel]

The brown wire at the ballast is only hot in Start, the double blue wire is hot in Run.

[fy469rtse]

thanks John, dino,
wasnt sure if there was a considered safe point to tap in engine bay ,
trying to keep everything neat as i can with all the extra's added to car,
that works well to tap in to wire at bulk head plug because i can keep it neat running with front loom to fans,
you have give me something to think about dino, if constantly wired in hot , heat sink could be an issue for fans to keep cycling on and draining battery,
just rewired a friends car this way because fans would not switch off , and kept cycling on and off that seemed like an hour or more,