Dirtbound electric fan wiring

[techno1154]

Engine temp has nothing to do with the AC condenser, which needs the extra cooling when it is on. As far as I know it is a separate system. One which turns on the aux fan on a timer for a reason.

Anybody got an idea on how to wire this in?

Two leads, one from the original aux fan harness into the relay, the other is the high signal lead from the thermistor/controller into the relay that controls the third fan. Maybe use a rectifier on both leads?

I'm no electrical genius, obviously.

Use the wire from the OEM relay that activates the fan when the AC is on to trigger the new fan relay. Spliced the wire into the wire from the temperature switch wire. You may need a diode to prevent 12 volts from flowing backwards and keeping things running when they are turned off,...but then again you may not need it.

 

[PRYAPSM]

I think that would be a single fuse for all three fans.

http://www.naxja.org/forum/showpost.php?p=245275675&postcount=21

Personally, I'd rather have three fuses, one per fan. That way a single short doesn't knock out all three fans. YMMV.

I ran a 30 amp inline fuse off the battery to a switch and then back to the relays. I haven't had a problem. I just did a write up on the dirtbound fans.

http://www.naxja.org/forum/showthread.php?p=245461998#post245461998

 

[tigerchief]

Use the wire from the OEM relay that activates the fan when the AC is on to trigger the new fan relay. Spliced the wire into the wire from the temperature switch wire. You may need a diode to prevent 12 volts from flowing backwards and keeping things running when they are turned off,...but then again you may not need it.

Thanks, diode is what I was thinking of, not rectifier. I thought this would work, I was just putting it out there to see if there are dangers doing it that I didn't know about.

 

[Corprin]

I am running a Corolla relay box with a 30amp fuse assembly running a DPST relay for my HID driving lights, a SPST relay for my electric primary fan, and a second SPST in reserve (could wire it, but nothing yet to wire to...yet).

Rather than running a SPDT relay for the dual-fan setup, I would leave out that splice and run the DPST relay. This will give you two "87" posts, not the useless 87a. This will keep the circuits isolated from the relay down; this helps diagnose shorts by just tossing in a common SPDT relay, switching the "trigger" on and off to see which circuit is not working, if both fail, the fault is upstream from the relay (needed this feature a couple times after some snow packed in the engine bay and melted... now relays are housed in the above box.