What was found
CREWS REPORTED SMOKE IN CABIN 12 MINUTES AFTER SHUTDOWN, SMOKE APPEARED NEAR FLOOR. MAINTENANCE RAN ALL AIRCRAFT SYSTEMS, FOUND SUPPLEMENTAL AIR CONDITION INOP, PULLED CENTER AISLE FLOOR BOARDS. APPEARS SUPPLEMENTAL AIR CONDITIONER MOTOR HAS BURNT SMELL. MAINTENANCE DEFERRED SUPPLEMENTAL AIR CONDITIONER IAW MEL 25-60-5-12.