i would just direct link it to a switch..if it still keeps on over heating when all this is fixed and the fan,water pump all work and the system aint cloged it could be a blown head gasket..pull the valve covers off and if it shows milky oil thats the problem..

also i'm just saying this just because this will save some one time on making a thread down the road if they have over heating problems and every thing is working fine.