As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CONT CAB ZONE TEMP LITE ILLUMINATED ON MATER CAUTION RECALL DURING THE DESCENT CHECK. THE LITE EXTINGUISHED WHEN MASTER CAUTION WAS RESET. GROUNDED - YES. VERIFIED FAULT. REPLACED FWD ZONE TRIM AIR MODULATING VALVE PER B737-800 AMM 21-61-21/401. OPS CHECK NORMAL. NO AIR LEAK NOTED. ETOPS SIGNIFICANT SYSTEM GROUND CHECK SUCCESSFUL.