Cadillac Repair: 1988 CADILLAC ELDORADO COOLING FAN, cadillac eldorado, failure points

Question
WHEN SHOULD THE FAN COME ON, AND HOW LONG SHOULD THE FAN STAY ON? MY FAN COMES ON AND STAYS ON FOR A LONG TIME.EVEN WHEN I SHUT THE engine DOWN, FOR A WHILE,  THEN TURN THE KEY TO THE ON POSITION THE FAN COMES ON . THE FAN WILL AGAIN TURN OFF AT SOME POINT. DO YOU THINK I HAVE A PROBLEM? IONLY OWNED THE CAR FOR SIX MONTHS  THANK YOU

Answer
Don,
There must be a run on older cars today! These are tough because there's just simply very little (if any) documentation around for such old stuff.
On your car, the BCM controls the fans via the fan control module. If the fan(s) are on when you first start the engine from cold, then there's a problem. Most likely it's the module. They used to be real common failure points.
I have no specific data on on/off temps etc for your fans but as I recall, the primary fan comes on approx. 215-220 degrees and runs until the temp is down to around 200-205 degrees.