What was found
SMOKE FUMES OF ELECTRICAL, AIR COND OR UNKNOWN ORIGIN. CHECK LIST PERFORMED FOR FAINT SMELL FROM A/C. CLEARED AFTER PACK 1 SECURED, LOUD HAMMERING NOISE FROM A/C SPACES UNDER COCKPIT. REMOVED AND CLEANED PACK NR 1, 2, 3 COALESCER BAGS PER MD11 AMM 21-54-05-2. RE-INSTALLED PER SAME. OPERATED ALL 3 PACKS INDIVIDUALLY AND SIMULTANEOUSLY. OPS CHECK OK PER MD11 AMM 21-53-20-5. NO DEFECTS NOTED. A/C OK FOR SERVICE.