! Two stage cooling fan controller for Gen 2 Coyote (will work for any engine) $115

[GTBradley]

​This is mainly for those guys out there that have a Coyote computer controlled radiator fan and don't like the noise it makes or the fact that it's always on. I hear lots of other engines use this very thing, so sorry if this is common knowledge, but I didn't find much help on the subject, especially for the Coyote setup. Though, you can use this on any build.

I have a real problem with the decibel level of my Factory Five supplied radiator fan, actually it comes from Maradyne. It appears to be a very good and capable cooling fan, but controlled by the Gen 2 Coyote computer (apparently not the case for other generations) it ends up running all the time at full fan speed. At 225 watts it amounts to some significant energy wasted too, especially considering this thing runs even at highway speeds - what is the sense in that? Even belt driven fans have clutches. Once it's on it won't shut off even if the engine gets below its on temp. Mine would typically turn on no later than 80 degrees C, and sometimes as low as 75. It's silly because the thermostat hasn't even opened at those temps.

This is an unfortunate design and reportedly it is this way because Ford was concerned that they didn't know what conditions these crate engines would be operating under, so they decided to err on the side of caution, as in, turn the fan on when the engine is on, run it at full speed and make it stay on. It is an inferred temperature that the computer determines based on sensors in the engine, but that fan has only an indirect relationship to the engine temp. What the fan affects directly is the radiator and keeping the radiator cool obviously keeps the engine cool. So I said, why not control the fan based on radiator temperature? Or better yet the coolant temp just before it re-enters the engine.

What I did to address this was to install a coolant sensor in the lower radiator return hose and fed that information to a Pulse Width Modulated fan controller. BTW, Maradyne makes the only one I could find that operates at half-speed and kicks into high when needed.



Controller part number MFA136 from Summit Racing $105 it includes the temp probe. Sensor adapter size is 38mm from Amazon $10.




The controller mounted nicely to the right side inner wheel panel (elephant ear) and the sensor wires were routed along the back of the fan.

The fan will run for an additional minute after the ignition is shut off at low fan speed, but only if it is connected directly to the battery. Remember, the controller controls the ground, not the power wire. So, you can either run the existing Coyote ECU fan wire to the positive fan terminal or a dedicated power wire of your own coming from a hot source (battery). In the latter case you'll need to dead end the Coyote wire.

In the video you'll see LEDs on the controller. At first the red LED is the only one lit and that means that ignition power has been turned on. After a few seconds the green LED lights up and you can hear the fan blowing at half speed. The center LED is yellow and it will light up when the fan is running at full speed, but that didn't happen in the video.

The fan runs significantly less than it used to and at low fan speed when it does. I set the on temp at 90ish degrees C, which means the fan doesn't come on at all at low driving speeds when in 50 to 60 degree F weather. It will come on when idling for extended periods, but it is quiet and very acceptable to me now. I love hearing the the pipes at idle rather than an industrial sounding fan.

Wiring details:

- Coyote ECU, ORANGE wire to fan positive terminal. (This doesn’t allow for 1 minute runtime after engine shutdown.)
- Controller LARGE gauge WHITE wire to fan negative terminal.
- Controller LARGE gauge BLACK wire to chassis or negative terminal on battery. (I used the existing wiring harness ground wire that the fan had been using.)
- Controller SMALL gauge BLACK wire to ground. (I used the panel the controller is mounted on, as this is a small electrical load.)
- Controller GREY wire to switched 12v power (I used the radio power wire, but I could have connected to the ECU wire.)
- Controller ORANGE wire to battery power. (I used the radio memory wire, as I don’t have a radio, but I could have omitted this connection.)
- Controller BLUE wire to temperature sensor.
- Temperature sensor housing screw to ground. It is a screw on the port housing that the ground wire will connect to. (I used the fan shroud near the sensor as this is a very small electrical load.)

The reason for the small orange wire going to my radio memory wire is so the controller could be used in the normal way (one minute run time) if I so desired in the future. The reason my fan doesn’t run the extra minute is because the coyote ECU fan power wire shuts down with the engine. If I switched to battery power instead of the ECU it would run for the extra minute. If you are not interested in doing it this way all you really need is power to the controller and the fan and they can come from the same place as long as it’s switched. In this configuration I would suggest using heavier gauge wire to the fan for power and grounding.

I hope this helps someone else.