rather than sidetrack the "Electric Fans" post currently going on in this forum, i figured i would start a new post.

anyway, i have a few of the supposed ford two speed fans. one of them is a dual fan from a 90's ford taurus SHO v6 and the other two are from a 99+ taurus.

all of these have the siemens motors with the 3 pronged plug, i have opened these up and found that 2 of the 3 prongs are joined internally. there is only one set of windings, and it doesnt matter which of the terminals i use, there is only one speed.

the SHO fan setup used an external resistor for the low speed(i know this for a fact), im not sure about the newer 99+ setup but i would assume it used one as well since the motors are wired the same internally.

for any of you that have these 2 speed fans, have any of you actually opened them up to see how they are wired inside???

if you have them setup to run in two speed operation, is there a noticable difference in fan speed by just switching terminals?

the reason i ask, it makes me wonder if these motors themselves are actually a 2 speed at all. i wonder if we arent wasting our time by trying to wire them for two speed operation without a resistor.

or possibly there are other motors out there to look for????

I have about 10 of the Taurus fans, none of which I've cut open but all have true 2-speed operation. Basically, there are three leads, brown, black and blue. The black is the common lead and goes to the negative side of the battery. Brown is the low speed connection and blue is the high speed connection. There are no resistors internal to the case, they would have to be quite substantial in order to drop the necessary power to significantly reduce the speed.

12v between black and brown produces low speed, and there is about 6.5V present at the open blue lead.
12v between the black and blue produces high speed and there is about 16.5v present at the open brown lead.
This indicates that there is a winding between the blue and brown leads, as it acts like an autotransformer.
The fan will also run at slow speed in the normal direction if you power the brown lead and ground the blue lead. If you reverse these connections, the fan will run backwards. If there was a resistor between the high and low speed connections internal to the fan, it sure wouldn't rotate, it would just burn up the resistor.

The fan will also run at slow speed in the normal direction if you power the brown lead and ground the blue lead.

if i did this on mine i would get a short, inside the motor the "blue" and "brown" prongs are tied together.

as i said, on mine there is an EXTERNAL resistor which is quite substantial. on the SHO this was removed from it was setup like this, black=ground, Blue went to positive and was activated by a relay. brown went to the resistor and was activated by another relay, evidently it was setup that when one side was powered the other side wasnt.

on mine it doesnt matter what i do. brown powered, blue powered or both powered, i get one speed only.

it doesnt really matter to me if i have a low speed or not, i just thought that it might save some people the time and aggravation. evidently there are different motors, so it might be a wise choice to test it out before going through and wiring it up for low speed operation.

I would make sure you have high speed working, and it's difficult to tell without a different speed to compare it to. Low speed on a Taurus fan is like most regular fans of that size, like a Proform Black Magic. When you switch to high speed, there is a huge difference in the amount of air that is moving. Most guys I demo these fans for are really impressed with how much air they move.

i am sure i have high speed, i have tested them every way possible. i can also tell you it is moving much faster then any other electric fan ive seen.

and you're right i am impressed by how much air they will move. one fan is impressive, with both fans on it will damn near suck my hand to the front side of the rad core.

i had installed these fans to help cool the car down between runs at the track, i was impressed at how fast they would cool the car. plus ive only needed one fan running to keep the car cool, although the real test will be in the heat of the summer.

i do have an extra motor that i could open and take pictures of, if you're interested.

I have a set of late Taurus fans but I do not believe they had a 3-prong connector. I also have the wiring diagram for the 2001 Taurus and you are basically correct about using the external resistor for low speed, at least in 2001. I got the whole wiring setup for mine and part of is a large ceramic resistor. I have measured the resistance values and doubt the slow speed is much slower than the high speed. I have a suspicion that the resistor/low speed is as much about reducing startup current as anything else.

Steve

strange, my later model taurus fans do have a 3 prong connector. it makes me think that there are numerous types of these motors out there, even between the same model car.

Most car manufacturers run different methods of regulating fan speeds as the models progress. Old school was to run separate relays for high and low speeds powering the "leg" of the fan necessary for the proper speed. The next progression was to run a one speed motor and use a resistor to regulate the amount of voltage supplied and therefore generate varying fan speeds. Now, most are running solid state relays which pulse width voltage at battery level but in varying durations to precisely control fan speeds; rather than a 2 or 3 speeds you have any speed from off to 100% and any level in between.

So, you could have fans from the same model but different years that operate in very different ways.