What was found
NOTICED BURNING SMELL WITH FLIGHT DECK FAN ON, WITH THE FAN OFF, THE SMELL STOPPED. FOUND RECIRCULATING FAN TO BE THE CAUSE OF SMOKE/FUMES IN THE COCKPIT. THE ITEM WAS TRANSFERRED TO DI 25211 AS PER MEL 21-20, CAT C. ADDITIONALLY, PERFORMED SMOKE IN THE CABIN INSPECTION IAW AMM 05-51-50, NO FUMES OR SMOKE NOTED. REMOVED AND REPLACED FLIGHT DECK RECIRCULATION FAN PER AMM 21-25-06. THIS CLEARS DI 25211 AND REMOVED PLACARD.