As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN TEMP FLUCTUATES. CREW UNABLE TO CONTROL TEMP IN AUTO OR STBY. NOTHING HELPS. TCV RESPONDS TO COMMANDS IN STBY. TRIM VLVS RESPOND COMMANDS IN AUTO. BITE AND VERIFY TESTS OF ZTC AND PTC'S NO FAULTS. SUGGEST OPEN A-C BAYS AND LOOK HARD FOR LEAKS. REMOVED AND REPLACED PACK TEMP SENSOR, LOW LIMIT VALVE & PACK TEMP CONTROL VALVE. RAN PACKS FOR FIVE MINUTES, CABIN TEMP NORMAL.