Since the compressor clutch is engaged by sending power to it you can add a power-switched Bosch-type relay to its circuit that will give your FiTech system a ground signal. You'd wire it like so...The Fitech efi system offers a black wire that allows for a programmable bump in rpm’s with compressor activation ...it also offers a yellow wire with a programmable electric fan activation at a pre-set coolant temperature...
I have been using the yellow wire to trigger a fan relay and it works great. Now I’m trying to get the black wire to do its job but I need an A/C ground and I am not sure where to find one. I see that the A/C binary switch can be replaced with a trinary that will send a ground signal but it makes sense that I should also tie it into the fan relay to activate the fan as well...
If I just tie the grounds together I’m afraid that I will bump my rpm’s upward every time the electric fan comes on...which would be ok but no ideal.
Has anyone recently tackled this idea ...?