Accel Thruster EFI + Electric Fans + A/C question

[BigBlockOlds]

Here is what I'm working with. I have a new Accel Thruster EFI system with dual-sync distributor for my 455 Olds setup that's replacing my failed Megasquirt attempt.

I'm trying to figure out how I want to wire in the trinary switch along with the electric fans to the Accel unit. I haven't been able to find any literature from Accel on something like this.

I know what needs to be done to wire the electric fans and the A/C clutch cut-out but I'm not entirely sure how I should go about adding the trinary switch to the system and how it might affect the other aspects.

Has anyone else wired in a trinary switch with an aftermarket EFI setup? If so, how did you go about it?

Thanks,

[BigBlockOlds]

Okay, so I've been doing a little more research and found some wiring diagrams online:

http://www.automotiverewire.com/Documents/ElectricFans.pdf

I'm thinking I can use a version of this schematic with my setup to get everything to work.

But a question I have is if I have dual electric fans, should I have the trinary switch wired to just the secondary fan? With the Accel Thruster ECM, you can control the fans independently of each other. So I am going to have one fan that will turn on at 170F and off at 160F while the second fan would be at something higher. Maybe on at 190F and off at 160F.

If I had the trinary switch wired into the main engine fan that would more than likely be running anyway, there could be a possiblity that maybe the AC system pressure could still rise and trigger the trinary switch. Of course this wouldn't do anything as the main fan is already running. So then the system would need to wait or hope the engine temps got high enough to trigger the secondary fan.

This is why I'm thinking the trinary should be wired into the secondary fan.

However, since the Accel EFI will automatically kick the electric fan(s) on when the AC is turned on, no matter what the engine temp is, do I even need a trinary switch? Could I not just use a binary switch instead?

Thanks,

[rayshake]

You could just use a binary switch with the ECU controlling the fans instead of the trinary. I also typically wire in a toggle switch in there just in case, to be able to manually switch the fans on if something goes bad in ECU ever. I rarely use a trinary switch. Maybe on a Carb'd car but not if you have programmable EFI.