As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPEN DESENT WHILE SWITHCHING PACKS FROM HOT TO COLD THE FA NOTICED A MUSTY SMELL IN THE CABIN-PERFORMED OPS CK OF PACK 1 AND 2 AND THE APU BLEED ENG 1 AND ENG 2 IDLE RUN IAW AMM 21-00-00-615-002 AND 21-00-615-004 NO ODOR DETECTED AT THIS TIME A/C OK FOR CONTINUED SVC