i did mine but i wired them both to 1 single switch. all i did was take all the original wiring out, replced it all with new wires, relay, temp sender and fuse then spliced a wire into them where they meet the fan. i then ran that wire to a 30a relay and then to a switch on the centre console. i then wired that to a 30a inline fuse which then continues to the live on the battery. never had any problems but then again i very rarely use the switch lol hope this is of some help mate.

p.s mine still kick in off the standard wiring and sender with no problems