Cooling fan clutch
 

I read recently that the radiator cooling fan (belt driven, mechanical clutch) should only reallly operate at low speeds and should disengage at road speeds. This is the 2nd clutch (bi-metallic spring) that I've had in this vehicle and the blasted thing howls like a banshee even at road speed - I'm talking 70-80 mph with 2500-3000 rpm on the tach. One qualifier - I live in south florida - but even at 5:30 a.m. this thing is running - a real fuel/power vampire as well. Is there a true mechanical clutch I can get as opposed to the temp activated clutch or am I screwed until I can replace the mechanicalwith an electric fan setup? Thanks in advance[8D]