As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
HEAVY VIBRATION IN CEILING BETWEEN LAV AND FLIGHT DECK. FOUND ICE BUILD UP IN NR 2 WATER SEPARATOR. REPLACED COALESER BAG, NO HELP. NR 2 ACM INTERNAL FAILURE CAUSING VIBRATION NOTED IN CABIN. COMPLIED WITH MEL REQUIREMENTS WITH LOCKING FCV CLOSED. REPLACED PAC 2 ACM REF MM. OP CK AND LEAK CK NORMAL, NO VIBRATION NOTED.