two speed fans

Can someone post a diagram reflecting how to wire a two speed radiator fan? I have a 1978 F100 with a Lincoln Mark VIII two speed electric fan. I have wired in a Power Distribution Block from a 1995 Taurus (currently using the blower relay and one of the ignition wires). I am currently using the blower motor relay for the fan but this does not allow two speed operation or AC operation. I would like to possibly run two controllers, one set for a 170* turn on (low speed) and the other set for 190* turn on (high speed) and also an AC override. The Power Distribution Block has a SPST and a SPDT relay and three smaller rectangular relay type units (what are these things?). These have five prongs each on them. Any help would be appreciated. Thank you

The fan is out of a 95 Ford Taurus. Three wire. Thanks

The three wires are going to be   Ground,  12volts for low speed, and 12volts for high speed.  You need to mount the fan, and try to figure out which wire is which.  Once you do that, I can help you with the relays to connect it as you desire.

holding the plug on the motor with the tang facing you, the wires are, from left to right , black(ground), orange(low speed), orange(high speed). connect the black to a ground. first speed: using a relay connect the center wire(orange) to term 87, connect term 86 to term 87a of the second relay, connect term 30 to a 12v source using 10ga wire and an inline fuse holder, connect term 85 to your 170 degree temp switch. second speed: relay for the high speed. term 87 to the next orange(high speed wire) and 85 to your 190 degree switch, term 87a to 86 of the first relay, term 30 to 12v on a 10ga wire with an inline fuse holder, and term 86 to a 12v fused source. if you dont want to cut the plug off the motor you can purchase the pigtail that plugs onto it and wire onto that instead(much nicer). the CARQUEST part number is S-725. the colors on the pigtail are: black(ground), purple(low speed), and blue(high speed).

Okay I will try this. The fan is already in and running on the high speed side with a temp switch set for 170*. I still need to know how to have the AC override both temp switches. The Power Distribution Block has two relays, one SPST and one SPDT. Can some one tell me what the "relay looking" things are that are silver in color? They have five prongs just like the relays. Thanks

okay, to get the ac to override, you need one more relay. wire every thing up the same as i described before except do the following: with a third relay, connect term 86 to the ac clutch coil wire, term 85 to ground, term 30 to ground, term 87 to term 85 on the high speed relay together with the wire from your 190 degree switch. that way when you kick on the ac, the high speed is actvated no matter what the engine temp is.

Thank you for the assistance. I will attempt to make it all work this weekend and let you know.

Will this set up need a diode on the fan power wire?

nope, no diode. ill be outta town till monday, but if you have problems just pm me. you should be fine.

I am considering using temp switches. Does anyone know where I can find a 160* and a 180* threaded type switch? 

sure, i'll even give you the part numbers for them. i need a little more info though. what kind of thread? pipe thread or metric? what size also? 1/4" pipe? 1/2" pipe? you know, that sorta stuff.

My mistake. 1/2 inch. Thank you for catching that.

well, heres the good news. i found the switches you need. the problem is they are the wrong thread. you will have to find a bushing adapter or have them made. the switches you want are not very common and alot harder to find thats for sure. the one for 160* is CARQUEST part number TS-231. the other is a CARQUEST part number TS-250. they are normally open switches that close when they hit those temps. they are a metric     22-1.5 thread though. nothing exists with your size thread or even any pipe thread that was at those temp specs. sorry

Thank you, I am impressed. I am not set on those temps. I could go -5 to +10 on the 160 and + or - 10 on the 190. Are these temps available? Also, do you know what would cause my two speed fan to run at what seems to be the high speed when connecting either the high or low speed wires to the battery as a test? I have two of these units and the other unit runs low and high (both speeds) when I test it straight to the battery.

just call your local store with those numbers. or better yet, if you have a chance go in and they have an illustrated guide so you can even see what they look like if they dont have them in stock.