Just did this and thought some others might have a need for it.

I installed an electric fan in my off road blazer and decided I didn't like all the noise it made when running full tilt and wanted the option of turning it down when full speed wasn't needed. (easier on the elec. system too)
So when I wired it in, I made it a two speed system.
It now has a high and low speed setting.

I tore apart an existing headlight relay system for my parts/pieces but they can be purchased separately I'm sure.
Used a three position toggle, on/off/on.
Got an old time ignition resistor from NAPA
Used the two relays from the harness and also reused the plug ends so if the fan needs to be removed it just unplugs.

The install:
Feed the toggle switch from under dash fuse panel.
Run two wires out to the relays.
Feed resistor from fender wall junction block. (already existing next to battery)
Take one leg from power side of resistor (12v) and the other from the open spade end of resistor. (4.5v)
Tie (solder) each fan lead wire from each relay together and run to fan as one wire then ground the other fan lead.

What happens is the full battery power goes directly through the relays to the fan not through the switch.
When running on high the fan draws 10.5 amps, on low it only draws 4.5 amps but still has a fair amount of air being pulled through the radiator and is very quiet, should be fine for idling and putting around on cooler days
The wires from the toggle switch don't even carry enough amperage to read on the meter. (nice)

As always use the proper guage wire size for your application and fuse it accordingly!!

I'm running this set up manually but it could easily be made to work as an automatic system with just a few additional parts.

I would look into this a little more. Some electric motors will not last long if run at a reduced voltage/speed.

I would look into this a little more. Some electric motors will not last long if run at a reduced voltage/speed.

DC motors are usually infinitely adjustable by varying the input voltage but I'll keep an eye on it.

The set up will be tested out thoroughly on an up coming wheeling weekend but to be safe I'm bringing a mechanical back up.

I noticed the fan blades are pitched as a pusher toward the front was that buy design?

I noticed the fan blades are pitched as a pusher toward the front was that buy design?


:dohh: wrong picture...

That was the first install trying to save space by having the fan motor tucked inside of the cowl and as you noticed it was 'pushing' the air but after some testing it was determined that their not pushing style blades and work alot better pulling, it's since been turned around. :rolleyes:

off road vehicle i'd be sealing those numerous crimp connectors with silicone or using the heat shrink waterproof connectors for reliability MY .02cents:)

off road vehicle i'd be sealing those numerous crimp connectors with silicone or using the heat shrink waterproof connectors for reliability MY .02cents:)

Good point, it's on the list. :)

I can't imagine forging through water that deep, I'd be sitting waist deep in it...:lol: but ya never know.

You can get the shrink connectors that you crimp and then either a heat gun or a lighter seals them. Most parts stores have them. they are longer and a translucent color. The 2 speed thing is a good idea

I thought the reverse direction maybe was an off road thing

what brand & size fan is that? it looks like it fits the stock shroud pretty well.

what brand & size fan is that? it looks like it fits the stock shroud pretty well.

It's been sitting in the garage for so long, I'm not really sure. :rolleyes:

Got it from another board member, I think it's off of a later model Camaro maybe.

Spent the weekend in Paragon doing some major wheeling in 80 plus degrees and the fan kept the engine right @ the 1/4 mark, no higher EVER. :metal:

Used low speed for warm ups and idling without issue.

Worked perfect the entire time, the set up's a keeper.

One year later, same set up and still working great.
Have since installed it in a big block shroud for better space between the fan and the water pump due to contact issues.

The only thing I've found is that the ignition resistor does fail, have had to replace that once so far.
The low speed is what fails, high is always available.

The other mod I made was to install two L.E.D. lights in the dash, green shows low speed is on and the red indicates high.

Yes, connectors are the heat shrink style now too.