W/O relays is simple.
Hot wire, fused 30A to terminal #3 on the switch.
Terminal #1 goes to #3 on the fan.
Terminal #2 goes to #2 on the fan.
#1 on the fan goes to ground.
Adding relays would be like this. The + 12 you could grab from the power supplying the fan power.
#1 on the stock switch is the 105 deg.C. #2 is the 95 deg. C.
#2 on the fan is low speed. #3 is high speed.
Somebody double-check me.
