As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON RECALL RECEIVED CONT CABIN ZONE TEMP LIGHT RESETS WITH MASTER CAUTION RESET. GROUNDED-YES. VERIFIED FAULT LIGHT ON RECALL. PERFORMED PZTC BITE, REF B737-800 AMM 21-61-00. PZTC2 FAULTED FLIGHT DECK TRIM VALVE ON BIT AND PREV FLIGHT, RESET ON VERIFY. AS PRECAUTION, REMOVED AND REPLACED CONT CABIN TRIM AIR MODULATING VALVE, REF B737-800 AMM 21-61-21. OPERATION CHECKS GOOD, REF AMM 21-61-00. LEAK CHECK GOOD. ETOPS GROUND VERIFICATION SUCCESSFUL.