so your fan is on a switch?
Yes and no; the switch decides if the DCC controller or the relay control the fan.
and does it only come one when it is needed to be on?
Only when the DCC controller is chosen to control the fan; if the relay is used, the fan stays on as long as the ignition is on.
i was gonna run the wires so it would only get power when the ignition was on, then only run when the engine needs to be cooled
i didn't really wanna deal with switches cause i don't plan many water crossings and i don't wanna leave it on and kill my battery
cause i already run lights and a sound system so i figured the battery will die easy with all that.
My switch is powered from an ignition source, which means with the key off, there is no juice going to the wire, which means no juice gets to th relay, so the fan cannot run if the ignition is off.