What was found
FOR FLIGHT 3712 THE CAPTAIN STATED WHEN HE BROUGHT THE AIRCRAFT IN HE HAD NO PROBLEMS. HE REPORTED HE LEFT THE AIRCRAFT THEN RETURNED LATER AND THERE WAS A BURNING SMELL IN COCKPIT. NO PASSENGERS WERE ON BOARD. THE AIRCRAFT WAS REMOVED FROM SERVICE. REMOVED AND REPLACED THE NR 2 DISPLAY SUPPLY FAN PER CRJ MM 21-24-12. THE OPERATIONAL CHECK WAS GOOD. THE ELECTRICAL ODOR WAS GONE. THE AIRCRAFT WAS RETURNED TO SERVICE.