As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING AFTER START CHECKLIST, THE AFT CABIN ZONE TEMP LIGHT ILLUMINATED. LIGHT GOES OUT ON MASTER CAUTION RESET. ACFT GROUNDED. AFT ZONE TEMP STILL ON RECALL, PACK TEMP CONTROL BITE NR 1 SHOW ZONE TRIM VALVE ON BITE & PREVIOUS FLT WITH RECENT HISTORY. REMOVED AND REPLACED THE AFT CABIN TRIM VALVE IAW AMM 21-61-21. OPS CHECKED GOOD.