Can a 7730 control a 2-speed Mark VIII fan?
 

I'm considering going with the Mark VIII fan. I was going to use a couple of Ford Starter solenoids to run the load and I was wondering if running the control power from those solenoids thru the ECM would be a problem. I can figure out the wiring, I just don't know if the current flow from picking up the solenoids is too much to be drawing thru the control leads and whether it's ok to use those solenoids for the relatively longer time (compared to a starter) that a fan runs.

I'm open to any pointers.

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

IIRC, the ECM only triggers a ground the connection for the relay which is very low current. You don't want to be running the fan power through the ECM, rather have the power run the through the relay and the ECM turn the relay on/off.


Also, there is a Fan1 on/off and a Fan2 on/off which you can control independently. I would imagine that you could rig it up to control one two speed fan.

That's what I was concerned with...
 

thanks....appreciate the feedback.

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

Those starter solenoids are gonna pull way too much current for the ECM drivers to cope with. They're severe overkill on cooling fans anyway. That fan is not gonna pull more than 20 amps tops, and the old starter solenoids are built to handle hundreds of amps. Just get some regular 5-pin 30A relays and everything will work fine.

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

You may want to look at a wiring diagram for a 95 LT1 setup. They use 3 relays to control 2 fans. I think you can use that scheme to control 2 speeds.

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

Not with the Mark VIII fan. IIRC the two speeds are controlled on the power side, and share a common ground (a 3-wire hookup.) For the LT1 type 3-way fan control the ground of the first fan is switched between ground and the power side of the second fan. That way the two fans can be powered in series for low speed, or in parallel for high speed. This means the two fan motors have to have independent grounds, which a 3-wire 2-speed fan does not have. I use the LT1 style controls in my IROC.

Since the two sets of windings in the 2-speed fan shouldn't be powered at the same time, you'll have to set it up so that the primary fan output from the ECM drives a relay which powers the low-speed windings, and the secondary fan output drives a 5-pin relay which removes power from the primary relay and powers the high-speed windings when the relay is energized.

I can put together a diagram of how to wire it if it's needed.

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

NO THEY WILL NOT!!!!!

The FORD fan like the MarkVIII fan will draw about 40 amps continously on the high speed setting and spike nearly 130 amps on start-up!!

The relay I used is Bosch part number 0-332-002-156 and is good for 75 amps continously with a 150 amp surge rating. Worked great.

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

http://www.fordmuscle.com/archives/2...8Fan/index.php

http://soderblom.net/bronco/tech/fan/

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

Did a little more research and you're right, that fan draws a ton of current! Pulls a lot of air too. Still, the Bosch 75A relay will be a lot more ECM friendly than a starter relay.

I'm considering using variable speed controller...
 

Seems to have pretty good rep....


http://www.dccontrol.com/


Now I need to figure out if I need the 35 amp or the 60 amp model?

Re: Can a 7730 control a 2-speed Mark VIII fan?
 

Why would you want to spend $$$ on a controller when the ECM can do a better job with a set of relays?

Oh, believe me, I don't want to....
 

I'm as much a bargain-hunter as the next guy.

One thing I liked about this controller is that it is variable speed, and that Mark VIII fan supposedly pulls a ton of air. Just pondering....still haven't received my Mark VIII fan so I'm just looking at options.

It turns out my 98 Mark VIII fan....
 

musta been variable speed!
From everything I can find out, it appears that the fan was variable speed which I suspect was varied by the Lincoln ECM/PCM.

When I received my new fan and went to test it, the center lead didn't do anything?!?! When I connected the 2 outermost leads the fan ran just fine and blew a ton of air. So I'm wondering, what the heck?

So, I start looking around the net and come to find out that somewhere along the way Ford must have changed the design from 2-speed to some sort of variable speed.....and they kept the same 3-terminal connector!

Anyway, after a little bit of research and some emails back-and-forth with some folks that own the Lincoln fan, I came to the conclusion that the center terminal doesn't do anything.....so I went and opened up the terminal-inspection-cover.....sure enough, the center terminal is just sitting there, brand new, not connected to anything. That's when all came together, it must have become a variable speed fan, over the 90's.

Nevertheless, here's the part numbers for the fan
MOTORCRAFT RF-64 and FORD F8LH-8C607-AA.