Fan Clutch on Tow rig

I just changed the clutch on my 02 F250 for the reverse reason--It never lock in when towing in hot weather and therefore the coolant would overheat. Mine is like described above--it has no wires going to it but has the spring that senses temp. change. Mine never worked from day one--Only took 11 years for me to figure out it was not working. BTW if you plan on changing it yourself it is right hand threads--was told by 3 different people that should have known that it was left hand. Another note is that it only overheated when towing in hot weather--never without 5er hooked to it and never in cool weather.