What was found
AT CRUISE ALTITUDE, EXPERIENCED A BLOWER VIBRATION INTERMITTENTLY IN THE COCKPIT FLOOR, BEHIND FLIGHT OFFICER. DURING VIBRATIONS, SMELLED AN ELECTRICAL BURNING ODOR. TRIED TO ISOLATE BY TURNING OFF CHILLERS, OVEN, AND LAVATORY FLUSH CYCLED CABIN FANS AND BLOWER EXTRACT FANS. TROUBLESHOT AND FOUND SOURCE OF VIBRATION AND ODOR TO BE THE EXTRACT FAN. REMOVED AND REPLACED THE EXTRACT FAN.