my fan was tempromental (worked some times and not other times) so what i did was
splice a wire right into the hot side of the fan wiring and wire that to a switch and a LED.
So that way it would tell me when it was on by lighting up the LED or I could manually force it
to be on by throwing the swicth.
The ground side is connected to a constant ground.
The hot side is the trigger side (switch side).
but like he said above it doesnt matter as long as you got hot and ground when you flip the switch.