I recently did the Motorcraft efan conversion using the fan off of a 4.6L XR7 Cougar. I used a wiring diagram found online. Using (2) 75a Bosch relays with
diode protection built in and a flexalite controller. Wired in a LED off of each relay, 1 for high and 1 for low speed. As shown in the drawing I put a 1n5404
diode on the hot wire going from the relay to the fan on each speed to ground. I first tried attaching diode at the relay terminal but I still got the
inductive feedback to my LED's. Next I tried using a wire tap and tapping
into the wire between the fan and the relay. Same situation as before. The diodes were installed with the banded end going to the fan wire and the other
to ground. Everything functions properly except the LED's. Diodes have been checked for proper one way flow. Hoping someone out there can offer a solution.

 

I can help you. Can you point me to the wiring diagram first? I designed my own wiring harness and relay setup for my E-fan setup. I used three diodes on mine. 2 to isolate the trigger wires to the relay and one to isolate an ignition wire when the fan was manually turned on. I'm pretty comfortable on most 12V circuits.

 

I don't have an exact wiring drawing but I can give you the place to find one that is similar. http://www.fordmuscle.com/archives/2...cfan/index.php
I used 2 bosch relays 1 for high and 1 for low using this setup. Manual switch
turns on high and temp controller or ac clutch turns on low. I didn't go from
the neg side of the fan with the diode, I went straight to ground. I have seen
a similar drawing that showed going to groung with diode. I figure that they
are basically the same point. LED's wired from relay terminal 87 to ground.

 

Are you telling me that you are not using the adjustable fan controller, but another bosh relay instead? or are you using the adjustable fan controller and two relays? Do either one of these relays have an 87a terminal?

You could also wire the LED's to the 86 on the relays and ground, or just simply across the coil.

If you are just running two relays and not the adjustable controller, I can draw up what I did with mine to give you an idea. It makes it a lot easier if one of the relays has an 87a terminal, but we can always work around that if we have too.

 

WhiteLightning1, Once you get the setup working I'll be PM'ing you! I have the Flex-a-lite VSC controller sitting on the shelf and was about to buy the Motorcraft RF-86 fan, however I didn't think you could get a two fan, variable speed controller working with a single two speed fan... This is great news! Subscribed

 

The adjustable controller is not a variable speed controller in this setup. The adjustablity is because it uses a temperature sensor not a switch and you can adjust the temperature that it turns on.

You can use this, you just need to make sure you have the correct sending unit for the temperature sensor. You might can still get it to work with just a temperature switch, but it would be almost useless at that point because all you would be using it for is to trigger a relay, which the temperature switch and ac clutch and do without the adjustable controller.

If it were me I would try to use the Adjustable controller. It will do a couple of things for you: 1. It gives you adjustability for the temperature your fan comes on. You just have to find the correct full range sensor which will cost a little more than a preset switch type sensor. 2. It eliminates the need to isolate the two different triggers (ac clutch and temperature switch) if you were using a relay without the controller. The JDM fan kit uses a seperate relay for this isolation (a third relay in your case), but I prefer to simply use a couple of 1amp or 3amp diodes on the trigger signals.

 

I'm getting a little off track...

You're good with this. Won't make any difference. And you have them installed the right way with the stripe to the hot side. If you want to see some smoke you can try and wire them the other way.

Are you sure you have 12V LED's? Like I mentioned before, try the 86 terminal to ground. It won't tell you if the main fusable link is broken but it will at least tell you if the control circuit is on.

When you say the inductive feedback...Are you saying they spike when you turn the circuit off?

 

I am using a flexalite temp controller along with 2 bosch relays. The feedback
is when I turn the fans off from the manual switch or when the fan is not running and the movement of air thru the fan causes the fan to spin and
act as a generator.

 

A regular diode like this one is just meant to only allow flow in one direction. I can't see where this diode wired this way does anything to help the inductive spike. If this were a zener diode that was set at 15-20 Volts it would bleed the voltage spike above the rating point to ground but that's not what you have.

If you relay has an 87a terminal (normally closed contact) You can switch the 87 and 30 connections and ground the 87a. This will ground both sides of the fan.

Or just hook the LED up to the control voltage on terminal 86 like I mentioned above and ignore the voltage spike. The voltage spikes might eventually cause wear on your relay contact, but being that your relays are plenty oversized they should hold up pretty well.

 

I'll probably just move the LED's to the 86 terminal. I was hoping to use LED's
as a troubleshooting device also but oh well. I had tried to figure out how
the diode was going to bleed off voltage spike too. I have seen at least 3 different fan wiring diagrams and they all have the diode in the same way.
Thanks for the input.

 

Is the problem the inductive spike or the generated voltage from the fan free spinning?
EDIT:
I really don't see what that diode's function is in that circuit. It may be something that existed on a prior circuit with a different configuration that no one knew to remove. It doesn't help with inductive spike, which is typically not that big of a deal on a fan of that size and it does nothing for the reverse charging. The only troubleshooting you will lose by putting the LED on the 86 contacts is whether or not you have main power to the relay contacts. You could do this with another LED if you want.