manual over ride switch

[coolbigrock]

hello,how can i wire in a manual over switch for my water to air radiator's cooling fan,i have a thermal switch but would like to put in one.

 

[EdgeLectrics]

Just wire a switch in parallel with the thermo switch.
Take the +12V feed from thermo switch, connect that to the switch you want and then connect the other side of the witch to a clean earth.

 

[coolbigrock]

k,best to have an inline fuse on the power line as well