What was found
UNKNOWN SOURCE OF SMOKE AND ODOR ENTERING CABIN THROUGH UPPER/REAR LAV AREA DURING FLIGHT FROM IAD TO ORF, DIVERTED TO NHK. AIR CONDITIONER AND GALLEY WERE SHUT OFF AND WE ISOLTED CABIN PRESSURE SOURCE TO RT ENGINE ONLY. ANY OR ALL 3 OF THESE ACTIONS CAUSED THE SMOKE AND ODOR TO DISSAPATE. INSPECTED AIRCRAFT AND ENGINE, NO DISCREPANCIES NOTED . INSPECTED ECS DUCT AND OP CHECK ECS, AIR CYCLE AND VAPOR CYCLE COOLING SYSTEM. ALL SYSTEMS OP CHECK GOOD, NO DISCREPANCIES NOTED AT THIS TIME IAW MM, CHP 21-50-00, 21-51-00,71-00-00. PERFORMED CHECK FLIGHT AND NO SMOKE WAS FOUND.