1989 Modial Cabriolet T Radiator Cooling Fan Help

Hello, I a new owner of a 1989 Mondial and recently my temp gage has been going past the middle mark. I did some checking and found out that the passenger/right side radiator fan is not turning on. I am confused as to when that fan should work. I checked with the Ferrari dealer and I got mixed answers. My questions are, Do both fans work simultaneously, or do they alternate? Also I am not sure if both are to cool the radiator or does the right one work when the oil temp is high? (a representaive at Ferrari suggested this). Do they have seperate sensors or just one?

I checked the fuses, relay & motor and they are all in working order on the fan that does not turn; so I am wondering if there is a problem, what should I do next? My car has 30,000 miles and is in excellent shape. I would grateful for any suggestions. Thank you, Sergio