Whelp, I finally bought an electric taurus fan and I'm gonna be doing the swap here pretty soon. I've been reading page after page after page of different wiring schemes and trying understand as much as I can (I'm AWFUL with electrical stuff). I know there's a whole bunch of electrical gurus here so I thought I might ask for some pointers. Heres what I want:

The taurus fan is a 2 speed and I would like to use an adjustable thermostat coupled with 1 or 2 high amperage relays (this thing needs it, peaks at around 80-90 amps on startup) to make use of both speeds, with the thermostat choosing which speed to use based on my engine temp. Also I would like a 3-way on-off-on switch (SPDT) to toggle as follows:

ON - thermostat controlled
OFF - kill fan completely
ON - forced high speed (thermostat bypass)

ON EDIT: I would like the forced high speed switch setting to also work when the truck is off, that is, independent of ignition (if possible).

The diagram that I have found most similar to what I want (and most simple), with the exception of the 3-way switch that I want, is this:



I know I'm asking an awful lot here but could someone use this diagram as a guide and add in the switch and an indicator LED to indicate when the fan is spinning. Also, if ya'll know which wires I need to tap in the engine compartment (location, color, guage, anything helps) please let me know, I'm totally in the dark here. Thanks a bunch.

 

I don't like the above circuit for several reasons.
Where did you get it from ??

It looks as if turning on your AC turns the fan on high, however it gives no provision for taking out the low speed which may be on at the same time.

Or is this motor supposed to use both the high and low speed windings while in high speed ??

 

I found it from one of the many fan install tutorials that I read online. I have no clue if it's safe or even if it works, that's why I posted it here. I liked it mainly for its simplicity and attention to detail. If you see flaws in it then please, by all means, draw me a better one!

Let me reiterate... I know NOTHING about electrical circuits, you might as well be speaking to a kindergartener as far as electrical circuits are concerned.

 

Also, the guy that drew that schematic used single pole double throw relays, but is that really necessary? For this application can't I use SPST relays? I don't know if there's a price difference anyway...

 

Disconnect the battery wire connection to 30 on the low side relay.
Connect a jumper wire from 87a of the high side relay to 30 on the low side relay.
That will only allow the low side to be on when the high side is off.

 

Like so?



How 'bout my switch and LED? Any ideas?

 

You need the SPDT to do what I am suggesting.

Actually the switch you want to add is pretty easy and the led's are easy too.
Do you want an led for low speed and one for high speed ??

A also suggest adding a 1n4007 diode across each relay coil to act as a spike suppressor like all relays used in computerized auto systems use.

I edited my first post asking you if the fan motor required both high and low speed wires to be on for high speed. Do you know ??

 

No, the jumper goes from 30 of the low side relay to 87a of the HIGH side relay.

 

2 LEDs would be nice.

And most of the schematics that I looked at suggested using freewheeling diodes soldered across from + to - on the fan motor to prevent the freespinning fan to generate a current when disengaged, is this what you are referring to?

And no, there are 2 separate wires for each speed and 1 common ground. Only 1 wire needs 12v at a time for it to operate.

 

A hah, like so:

 

OK, you definately need the SPDT relays.
You definately need the jumper I suggested.
There is no need for diodes across the motor windings but they wouldn't hurt.
You do need diodes across the relay coil with the banded side going to 85 and the unbanded side going to 86 on both relays (spike suppressors).

 

No

The wire from 30 on the LOWER relay goes to 87a on the UPPER relay.

 

Okay, like so?

 

Woops

I had to refresh my browser.

That's it !!!

 

Okay you seem pretty competent with your wiring skills, can anyone else confirm the functionality/safety of this setup?

Thanks for the help netscanner. Also, how do I wire the switch and LEDs?