AC fan wiring - Mark V

[rickster991]

I figured out most of the wiring for the AC. I hope. I posted the schematics I used in my build thread. I would appreciate anyone with experience to have a quick look and let me know if I did anything wrong. The last bit to hook up is the radiator fan. In different parts of the build manual / AC instructions it mentions cutting into the fuse panel for the fan relay as well as running separate "power wires" to the fan depending if you have the ECU controlling the fan or the AC. In some places it mentions connecting multiple wires together at the relay and multiple wires together at the fan itself. Do you need to worry about feedback? I am really confused and don't want to mess this up. Does anyone have a clear schematic of how to wire the fan with AC and ECU control? Thanks for any help!

[edwardb]

The short answer is both. The fan can be triggered by the A/C system via the trinary switch or the normal ECU trigger based on engine temp. Even if both at the same time it's OK. Questioned it myself on my first A/C build and Factory Five assured me it was OK. Two builds wired this way and they work fine.

[rickster991]

The short answer is both. The fan can be triggered by the A/C system via the trinary switch or the normal ECU trigger based on engine temp. Even if both at the same time it's OK. Questioned it myself on my first A/C build and Factory Five assured me it was OK. Two builds wired this way and they work fine.


The trinary switch goes to to the ground of the fan relay? The schematic says Green fan thermo scwitch wire. Where does the ECU go, directly to the fan? Or I guess I can splice it into the wire in the harness that's going to the fan?

Thanks again!

[edwardb]

The trinary switch goes to to the ground of the fan relay? The schematic says Green fan thermo scwitch wire. Where does the ECU go, directly to the fan? Or I guess I can splice it into the wire in the harness that's going to the fan?

Thanks again!

Don't overcomplicate it. Wire each (A/C and ECU controlled fan) as separate systems. Wire the A/C system exactly like the FF schematic shows. I don't have it in front of me but I followed it exactly for both installations I've done. I found the schematic at the end of the instructions more useful than the wire-by-wire through the bulk of the instructions. Helps me anyway to see the big picture and try to understand what is happening. Wire the ECU controlled fan exactly like your EFI instructions show. I've done Coyote and LS ECU control fans and they were the same. I can't say exactly what yours will be but I expect the same as well. While the end result of each (A/C and ECU controlled fan) is to run the cooling fan, the trigger for each is different. I don't know how to explain it any better.

[rickster991]

Thanks!