Cadillac Repair: 89 catilac eldorado 4.5l engine, catilac, engine temp

Question
this is a very quick  one the cooling fan only come on when i turn the ac on. i have jump the fan and it works. i 've ran the engine and unplugged the temp sensor and the fan did not work what could it be?

Answer
The bigger cooling fan will come ON when the engine temp reaches approx 220 degrees. If requested by the computer the smaller fan may also come ON depending on the temp of the engine.

Normally only the big fan will come on when it reaches normal engine temp and the smaller cooling fan will ALWAYS come ON when the AC is in operation.