The finished product.









From the bottom

 

Its not an exact fit but it is VERY close. I probably trimmed away too much and you can see in that picture I still didn't remove a lot. If you have a jig saw with a smooth cut blade it cuts very easy.

The flex a lite variable speed controller I used connects straight to the battery for supply and ground. Then a connection to a circuit that turns on with the key, and a connection to a circuit that goes to the AC ( the unit has two inputs so if the AC circuit you taps grounds and one for hot). I tapped both the switched power and AC circuits at the small junction box on the drivers fender.

Here are the instructions.
http://www.flex-a-lite.com/pdf_instr...1163-91163.pdf

 

I have not done a lot of testing yet I just got it all finished up but so far it seems great. I have the unit set for around 195. This controller has a soft start so that you don't get a spike of current as you would with just a relay. Also the fans come on at 60% at your set temp. and then ramp up to 100% if the temp. increases 10 degrees. When the AC comes on the fans start at 60%. 60% is a LOT of air with this unit.

The controller has an input to manual override the fan OFF, and an input to manual override the fan to 100%. When you first turn on and start the engine there is a delay so the fan is not trying to run with the starter. Also I think the fan will run for a small time if you turn off the engine above the set temperature. (as much air as this moves I don't see that happening).

After I play around with this some more I will report back.

 

So, if the AC is turned on the fan will also be on correct? At what percent of power? And how about highway speed does the fan turn ON if AC is on?

Have you listen to fan ON yet? How loud is it? Thank you.

 

Awesome write up!!! Thank you!

Do you happen to have any pics of this junction box you tapped into?

Have you gotten the fans up to 100% yet?

 

Hi.

Very nice write-up.

I do have a couple questions, though.

You no doubt are aware of an RF-269's spec:

Small fan

Diameter 14.5"
Hub diameter 5.5"
Current (no load) 24.83A
Current under load 26.24A
Starting current 69.64A
cfm (no load) 2797 cfm

Large fan

Diameter 15"
Hub diameter 5.75"
Current (no load) 27.64A
Current under load 36.35A
Starting current 69.64A
cfm (no load) 2964 cfm


Total

Current (no load ) 52.47
Current under load 62.59A
Starting current 139.3A
cfm (no load) 5761 cfm

Is the VSC controller truly rated to run these reliably, long-term? What is the rating of that controller ( and what fuse size is used, wiring size used )?

Note that the specs for a RF-269 are far more demanding that a FAL 270 dual efan assembly. Which is why I'm asking this. At full rpm, moving full rated airflow as installed against a rad (e.g. under load), an RF-269 draws almost 63 amps continuous, both fans running.

Second - For myself, I think for that (very similar) price a DCC constant temperature controller is more robust and a better 'fit' ( not ot mention a better controller). DCC has specifically tested it's controllers with Motorcraft fans, including the RF-269 model. Hence, if yer VSC ever fails, consider a DCC replacement. Their controllers can easily supply > 80 amps of continuos power. Just sayin'.

good luck

 

Thanks for the info MGD!

I'm going to read up on this controller.

 

ive got the same set up that you installed and i will second MGD's suggestion on the DC Controls controller. ive got the fk75 model and it works perfectly with the set up. these fans take up a LOT of power when they turn on! Ive also got one of the older DC Controls set up for my Mark VIII fan on my expedition i use for offroading. Theyre extremely reliable!

 

The pic of the box is in post #10 it had one relay and the diode to snub the AC clutch. No I have not gotten the fans to 100% per the inputs here this controller does not have the capacity to sustain it if I did! The set point now is 195 and over 10 degrees it would ramp to 100%.

 

MGD,

The controller is rated at 45 amps but has an inline fuse of 40 amps. At the 60% AC engagement I measure 17 amps from one fan. Inrush (start up) current is not an issue since it has a soft start mode that slowly ramps the PWM until the motor builds up back emf. My issue with this controller will be at 100% I will be in danger of popping the fuse. The wire to the battery and fans is 8 gauge.

Did you do the design the DCC? Did not know about them, I will check them out.