What was found
AFT LAVATORY SMOKE DETECTORS WENT OFF APPROXIMATELY F/L 220. AFT FLIGHT ATTENDANT REPORTED HEAVY ELECTRICAL SMELL. MINUTES LATER LEFT AFT LEFT LAV SMOKE DETECTOR WENT OFF. INSPECTED AIRCRAFT FOUND LT PACK OVERHEATED AND DUCT BLOWN OFF ACM. PRESSURIZED A/C TO 4.0 DIFFERENTIAL WITH RIGHT PACK, NO SMELL NOTED. RESECURED LINE IN CABIN BETWEEN RIGHT AND LEFT PACK AND RESECURED INLET DUCT TO LEFT ACM CLAMP.