Fast XFI - and using A/C and second fan control

[GregWeld]

I'm helping a buddy with his 'last mile' - Fast XFI - and he wants to be able to control TWO fans independently. He wants one fan to come on with the ECT control - that's easy..... but looking at the instructions and pin choices - the A/C control and second fan is a bit confusing to me.

I see AUX # 3 (ECU Main pin 3 output) has a couple of controls for this output. Easy - %TPS and ECT

I also see there is a A/C "enable" pin B11 - that can hook to the NEGATIVE side of a relay... but this is a pin OUT I assume and has a 2 amp capacity.. plenty for switching a relay.

What I don't see is an A/C INPUT.... in other words - how would the ECU know the A/C has been turned on... I can't find this anywhere in the instructions.

HELP! I hate calling the tech lines....