As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLT - CREW REPORTED THE AIR CONDITIONING HAS A PUTRID SOCK SMELL. MAINTENANCE RAN BOTH PACKS WITH ENGINES AND APU. DID NOT SMELL ANY FOUL ODORS. REPLACED BOTH LT AND RT RECIRCULATION FAN'S HEPA FILTERS. REFERENCE MM 21-21-23 AND 21-00-01-1. AIRCRAFT OK FOR SERVICE.