There is a myriad of conflicting information on Mark VIII fans. Nobody seems to have it all right. I have read through 2 dozen threads and have called a couple shops that sell these trying to figure this out. Here are the results of my research -
I know for a fact that there are three part numbers for the Mark VIII fans as follows:
93-96 F3LY 8C607 A 1100 on low and 1850 on high RF123 Y=lincoln/mercuy
97's F7LZ 8C607 AB 1800 on low and 2225 on high RF56 Z=ford
98's F8LZ 8C607 AA 1800 on low and 2225 on high RF64 Z=ford
All these fans are single speed PWM controlled by the car. I believe the middle wires on ALL of these are either tied together at the motor; or don’t exist (It has been reported that 97 and 98 have only two wires in their pigtail).
There are several stock pigtails that have been reported as taken from Mark VIIIs:
2 black 1 green (all same gauge, blacks tied together at motor)
2 black 1 blue (all same gauge, blacks tied together at motor)
1 black 1 brown or orange 1 Blue (different gauges for the positives)
1 black 1 Org/Blk - Low 1 Blue - High (different gauges for the positives)
1 Black 1 BRN/Org - Low 1 Brn/Yellow - High (different gauges for the positives)
I don't believe that Ford was putting different harnesses in the engine bays within a model year and I doubt it changed between 93-96 particularly the ones that have differnt gauge wires. If this were true I have yet to see a wiring diagram that proves it.
RF123 75717 Mark VIII 93-96 (1-speed 18" ?)
RF24 75715 T-bird LX 94-97 (2-speed 18" ?)
Cougar XR-7 94-97
RF125 other Taurus GL 90-95 (2-speed 16" ?)
Taurus L 91-92
Taurus LX 90-95
Taurus SE 95
Continental Executive 91-94
Continental Signature 90-94
I think the confusion lies with the RF24, It has the unique Mark VIII fan blades and shroud but a different motor. This is a true 2 speed motor; presumably these cars don’t have PWM controllers and just use two speeds whereas Mark VIII can achieve multiple speeds by PWM. I think this fan is mistakenly referred to as a MarkVIII fan. This helps explains all the different wire colors and sizes that are reported as being a Mark VIII pigtail. The shroud and fan blades looks identical but the middle terminal on the RF24 motor is not a "dummy". The plastic plug at the motor is black instead of white and it does not have the “inspection cover” near the plug. I suspect RF24s were assembled in Canada and RF123s were assembled in Mexico which accounts for that misconception. Presumably, high speed on the RF24 motor is not as good as the M8 motor wired straight to battery but I have read threads that say high on a 2speed is better than the single.
*** UPDATE *** I pulled the fan blades off my 93 1-speed and the motor is #F3LU - 8K621 - AA and is stamped CANADA. It crosses to a #75717, so that blows up this 2 speeds come from Canada story. I have also learned that the two-speed motor is #F4SH-8K621-AA which crosses to a 75715 *** UPDATE ***
I have read threads where the author swears that he pulled the fan himself from a 93-96 Mark VIII and it was a black plug 2speed. IF this is true and that is a big IF; I suspect that Ford, in a pinch, would sustitute an RF24 if they were out of stock on RF123s for the 93-96 model. Theoretically the VCRM wouldn't care which was there since both fans have 2 wires that are positive and one ground. I bet due to the way the VCRM pulses based on conditions (engine temp, A/C, etc); the net cooling effect is the same whether both positives are one speed or two. The reverse however is not true. You can't put an RF123 in a T-bird/Cougar, although the fan blade and shroud are the same. Their relay system expects 2 different speeds depending on wich lead is energized. You would be on high all the time which is not desirable due to the current draw and startup spike.
As for the notorious "Taurus fans"; the RF24 and RF125 are both 2 speed motors but one drives an 18” fan (RF24) and the other drives a 16” fan with a curved blade and differnt shroud (RF125). Neither on high is as powerful or pulls more air than any of the three Mark VIII fans (RF123, RF56, RF64). On a side note, it appears that regardless of whether you have a 1 or 2 speed; any fan having 12v on both positive wires at the same time is not good. It makes high speed slower on a 2-speed and can affect the life of the one speed.
There is a pdf on the net that does an airflow and current comparison of "Mark VIII 2-speed" and a couple Spal fans. In the second post the guy admits that he doesn't know what the part number is of the fan he tested. He just said it was one of the "big ones from a Mark8". I think he had an RF24. This is the original thread it was posted in:
I believe all my data is correct. Let me know if I am wrong on any of this that you are SURE about. Also, I have a couple mysteries I am trying to get confirmation on:
1) Is the RF24 (T-bird/Cougar) on high really not as good as RF123 (M8)? Did maybe the person who tested this have both positive terminals connected on the RF24?
2) I believe the RF56 and RF64 spin faster but with a different blade design (presumably to make it quieter). Do they move more air than the RF123? I have read opposite reports on this.
3) What is the difference between an RF56 (1997) and an RF64 (1998)?
4) I bought a ’93 Mark VIII fan from a local yard. It has a white plug but is missing the “inspection cover” near the plug. Attached is a picture from a thread I read pointing out how to spot a 1-speed vs a 2-speed and a picture of the one I bought. Could the inspection cover be for an RF56/64? Maybe a slight redesign of the unit back when they were making the 93-96?