What was found
CMH TO BOS - ON INITIAL CLIMB, THE CREW RECEIVED A MASTER WARNING AND EICAS MESSAGE FOR BLEED 2 OVERTEMP. AFTER RUNNING THE QRH, IT WAS DECIDED TO RETURN TO CMH, WHERE THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT THE FAULT TO THE FAN AIR CONTROL THERMOSTAT, AND AFTER REPLACING IT, THE NUMBER 2 BLEED SYSTEM OPERATED NORMALLY.