As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT PACK FAILURE, RTFL. NOTICED WHEN DOING LEAK CHECK ON UPPER FCV THAT THE LOWER FCV WAS FLUCTUATING OR SURGING. REPLACE THE AIR SUPPLY CABIN PRESSURE CONTROLLER PCN 566-9019 FOR LEFT PACK FLOW CONTROL VALVE NOT BEING ABLE TO BE SHUTOFF. REPLACED ASCPC PER AMM, OPS CHECK GOOD AT THIS TIME.