What was found
ON TAXI OUT, A VERY BAD SMELL THROUGHOUT AIRCRAFT (MUSTY LOCKER ROOM TYPE). PASSENGERS AND FLIGHT ATTENDANTS COMPLAINED OF SMELL. RAN PACKS IN HIGH FOR A SHORT TIME AND ODOR SEEMED TO DISSIPATE. NOTE: ODOR DISSIPATED PRIOR TO TAKEOFF AND DID NOT REOCCUR DURING FLIGHT, LANDING, TAXI OR NEXT ENGINE START. MAINTENANCE ACCOMPLISHED TROUBLESHOOTING OF CABIN ODOR IAW J/C 03L00021001. NO ODORS DETECTED. HEPA FILTERS REPLACED PER J/C. SUSPECT INITIAL ODOR DUE TO GROUND AIR START UNIT ON INITIAL RUN OF ACM.