My coolant fans will not come on and my car is overheating what is the problem? on 1995 Chevrolet Caprice

If I leave the car in idle it will start to overheat, a personal mechanic looked at it already but not at a shop so could not diagnose why the fans were not coming on unless I turned on my A.C.

Asked by for the 1995 Chevrolet Caprice
If it comes on with A/C the problem most likely the radiator fan switch.This switch job's to control( close and open) eletric circuit on a given temperature.