As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ACCOMPLISHING A TEST FOR THE RT PACK, THE LT PACK TCV IS INDICATING FAULTS, NR 1 ZONE TEMP CONTROLLER SHOWS TCV FAILED, VERIFY TEST. ACFT GROUNDED. PERFORMED A BITE TEST OF THE NR 2 PACK ZONE TEMP CONTROLLER AND FOUND TCV FAULT IAW AMM 21-51-00-700-803. REMOVED AND REPLACED THE LT PACK TEMP CONTROL VALVE IAW AMM 21-51-10-000-801/400-801. BITE TESTED GOOD. LEAK CHECKED GOOD.