As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON MC RECALL (AFTER START CHECK) AMBER ZONE TEMP FOR CONT CABIN ILLUMINATES - EXTINGUISHES UPON RESET. GROUNDED - YES. PERFORMED ZONE TEMP CONT BITE TEST. VERIFIED RED LIGHT ON ZONE TEMP CONTROLLER 2 AND FLT DECK TRIM VALVE INDICATION. REMOVED AND REPLACED RH ZONE TRIM AIR MODULATING VALVE PER B737-800 AMM 21-61-21-020-001/400-801. PERFORMED ZONE TEMP CONT BITE TEST PER AMM 21-61-00-700-806-002. OPS CHECKED GOOD. NO OTHER DEFECTS NOTED.