As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON MASTER RECALL AFTER START CHECKLIST CONT CABIN ZONE TEMP LIGHT ILLUMINATED AND RESET AFTER MASTER CAUTION RESET. GROUNDED-YES. REMOVED AND REPLACED CONT CABIN ZONE TRIM VALVE, IAW B737-800 AMM 21-61-21. OPERATIONS AND LEAK CHECK GOOD.