Radiator Fan wiring, Gen3 Coyote with A/C & Flex-a-Lite fan

working on the radiator fan wiring, still waiting on my Coyote ECU/PDB setup from Forte...

overview of parts: (think FFR Gen3 coupe with A/C)
RF harness
Gen3 Coyote ECU
A/C kit with Trinary Switch
Flex-a-Lite Wave LoBoy Puller 16" fan

there are 3 wires in the RF harness
Black: Radiator Ground
Blue: Cooling Fan
Dark Green: Thermo Switch

2 wires on the Flex-A-Lite Flex-Wave LoBoy Puller Electric Fan
Red (+) on the puller fan
and Black (-)

I'm a bit conflicted as to what controls the fan at this point
- Coyote ECU, ORANGE wire to fan positive terminal which I assume is the BLUE wire
the Fan Black(-) goes to ground on the RF harness

from the instructions below, does the red/blue trinary switch go to the dark green thermostatic wire on the harness?
also, it shows the BLUE wire in the A/C harness going to the fan with the engine control wire, is this spliced with the Orange ECU wire?


A/C Instructions:
Attachment 163136

What you're going to end up with is two ways the cooling fan can be powered. (1) From the Coyote Cooling Fan Feed (Item I in the Ford Performance instructions, orange as I recall). This needs to be routed to the positive side of your cooling fan. Either directly or via a connection to the RF blue cooling fan wire somewhere. Note this connection will power the fan on/off based on control from the PCM and engine temp. (2) From the RF cooling fan circuit. In this case, the dark green thermo switch is routed to the A/C trinary switch. When the switch closes (based on A/C system pressure) the thermo switch wire is grounded and the RF panel powers the cooling fan.

My Gen 3 Coupe with heat and A/C is wired this way and works perfectly. My current truck build is also wired this way. Note this is also what the A/C instructions from Factory Five describe. Although IMO they just say what color to attach to this and that. But don't describe the theory behind very well. So it's a bit confusing. After sorting it out during my Coupe build, I asked them if it was OK to have the fan powered from two different potential sources. They said it was, and has turned out to work fine. Hope this helps.

Quote:

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Originally Posted by edwardb

What you're going to end up with is two ways the cooling fan can be powered. (1) From the Coyote Cooling Fan Feed (Item I in the Ford Performance instructions, orange as I recall). This needs to be routed to the positive side of your cooling fan. Either directly or via a connection to the RF blue cooling fan wire somewhere. Note this connection will power the fan on/off based on control from the PCM and engine temp. (2) From the RF cooling fan circuit. In this case, the dark green thermo switch is routed to the A/C trinary switch. When the switch closes (based on A/C system pressure) the thermo switch wire is grounded and the RF panel powers the cooling fan.

My Gen 3 Coupe with heat and A/C is wired this way and works perfectly. My current truck build is also wired this way. Note this is also what the A/C instructions from Factory Five describe. Although IMO they just say what color to attach to this and that. But don't describe the theory behind very well. So it's a bit confusing. After sorting it out during my Coupe build, I asked them if it was OK to have the fan powered from two different potential sources. They said it was, and has turned out to work fine. Hope this helps.

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Thanks Paul - I figured you're one of the few that would be familiar with this issue...
my son and I were noodling all day yesterday over this and came to the similar conclusion that there are two signals that can trigger the fan, via ECU and via Trinary switch
I do remember reading in your Coupe build that the A/C systems does need some amount of charge to actually trigger the trinary switch so we will keep that in mind..

I believe from the directions, I'll route as described:
Orange from ECU and Blue from RF Harness to the (+) on the fan
Green RF Harness to Trinary Switch Blue/Red
Black RF to Black on the fan, or possibly just ground the fan to the frame?

Quote:

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Originally Posted by toadster

Black RF to Black on the fan, or possibly just ground the fan to the frame?

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Either way works. Since the RF harness has the ground wire for the fan, I use it through a 2-pin connector along with the +12V wire so the fan can be easily disconnected if needed. But going directly to the chassis with a solid connection works too.