Anyone contemplating an efan conversion knows that the Taurus 2-speed electric fan is one of (if not the) most popular options.
It fits the radiator well and cools adequately.

Since I installed mine last summer the fan has performed perfectly but I only had the low speed hooked up- mainly due to wiring considerations.

Yesterday, while cruising through the junkyard, I found an excellent solution to the wiring issues...the fan control module from a Volvo 940.
This unit incorporates everything you need* into one clean,compact part and was cheap (mine cost $5 including a generous amount of harness).

Here's a picture of the module (bill for size reference):


The single large gauge red wire is +12v from a switched and fused power source.
The two heavy wires on the left go to the fan and the two lighter gauge wires in the middle go the fan sensors (or switches).

Here is a schematic so you can see how it operates:

Basically, grounding terminal B1 (either with a thermoswitch or a driver operated manual switch) allows power to the green output wire- the low speed to the fan.
Grounding terminal B2 kills the low speed circuit and activates the red wire- high speed to the fan.
Couldn't be simpler.

On the back of the module are two clips- in the Volvo this part just slid over a piece of sheetmetal...you may have to experiment/modify to mount in the RX.

All in all, this looks like an excellent way to compliment and simplify your efan install.



*Excluding a fuse assembly (I'm using the 30A circuit breaker module from the Taurus I pulled the fan from) and the two sensors to trigger the fan.

 

write up needed

 

^^^PLEASE, I got one of these...I think.

I got it from a taurus but I heard it was the mark VII that had the 2 speed.

 

Write up of what?

If your fan has three wires, it's a two speed.
Two wires and it's not.

 

Keep re-reading post #1 until it takes hold in gray matter.

 

That's not entirely true...it applies only to the Taurus fan, not the Mark VIII

First, let me say that I have never seen anything except the two-speed Taurus fan on the 3.8L engine.

On early model Mark VIII, the fans were two-speed and the plugs are three-wire. They are interchangeable with the Taurus plug.

On the later model Mark VIII fans, there are still three wires but the fans are just a single speed-HIGH. One of three wires is non-functional. These later model Mark VIII had PWM controllers rather than the two-speed of the earlier models. I think they just reused the harness, and if a two-speed fan were plugged into the PWM, it would function correctly.

And my testing of the mighty Mark VIII tells me that the fan pulls only a couple more amps than the Taurus fan, but still under 30 amps. The motors are the same, but the Mark VIII is an 18" monster. They move more air on high than the Taurus fan.

One of these days I am going to sell my Taurus setup and install a Mark VIII with PWM setup.

And nice find on the Volvo setup, Clokker!

 

So does this eliminate the need for any other relay or thermo switch? Does it come on/off with the car and kick up with the ac?

 

It doesn't require any other relays but you still need two thermoswitches (or manual switches) to trigger it.
Whether it's always hot or not depends on where you get your main +12v.
If it's not ignition switched, the fan will run till the trigger disengages (i.e., even if the car is off).

Basically, all the Volvo unit does is automatically switch between low and high fan speed.
Everything else is up to you.

 

Here is how I would apply this module:

I would trigger the low speed with a 200* on/185* off switch. http://store.summitracing.com/partde...art=SUM-890018

I would trigger the high speed with the A/C compressor.

I would use a 75amp Bosch SPST relay to apply main voltage to the unit when the ignition is on.

Done.

Ok, I might be tempted to wire a 235psi on/175 psi off pressure switch mounted on the highside of the A/C system into the highspeed fan trigger circuit. That way on the highway or on cool days the high speed will not run if the A/C pressure is low enough.

Nice find, Clokker.

 

That would be a great setup.
For cars without AC (like mine), the high speed trigger could be a second, higher temp thermoswitch or even a driver activated manual switch.

The need for the the high speed is very dependent on climate and driving conditions.
Living in Colorado and not commuting (therefore, very little sitting in rush hour traffic), I've not yet needed the high speed function- low speed has been perfectly adequate.
This module will just allow me to have the fan wired in a very factory-like way, whether it gets used or not.

 

One more observation on this unit. You do realize that this unit is just 2-SPDT relays integrated into one housing? All the 'complicated' connections are done inside the housing, leaving only straightforward connections to the unit.

This is almost exactly how my 2 relays are wired. The only difference is that my compressor activation does not pull the signal to ground but rather supplies 12v instead. It requires a couple of changes to the 'complicated' connections to make it work. I could add another relay to my setup to enable the 12v supplied to pull to ground. That would allow the high speed to be enabled by the compressor and/or a higher set temp point.

That function is supplied by the ECM in your schematic, (the A/C compressor and/or high-temp set point function). A relay would need to be added to make the Volvo module work with the A/C as well.

 

I need the 2 speed out here in summer. Me= las vegas. Hope it cools enough

 

Very nice

 

Well, yeah...I do realize that.
It's the integration and exterior simplicity that make it so attractive.

Of course, should the unit fail, it would be more expensive to replace.
New, it's around $70, whereas your separate relay setup would be much cheaper (assuming only one relay failed at a time).

Fortunately, I just snagged a second Volvo unit at the junkyard today, so I have a backup should it be necessary.

 

I have ordered my Koyo radiator and am going to run a Taurus e-fan. I am sort of curious what will be required to achieve the most efficient setup.... I plan on eliminating my current clutch fan and therefore eliminating the stock fan shroud. I am not an experienced mechanic (as may be assumed by my plans, not sure if they are "proper" or not). I guess I am looking for input as far as locating the fan. Pictures would help! Thanks.

 

youve got some more searching to do my friend