What was found
CONT CAB "ZONE TEMP" ON MASTER CAUTION RECALL. RESETS WITH MASTER CAUTION. GROUNDED-YES. PERFORMED RT PZTC BITE AND FOUND FLT DECK TRIM VALVE FAULT ON BITE. NO FAULTS IN PREVIOUS FLIGHTS OR IN VERIFY. PERFORMED BITE/VERIFY TEST NUMEROUS TIMES LISTENING AND WATCHING FLT DECK TRIM VALVE OPERATION. OPERATIONS NORMAL. RESET SINGLE FLT DECK TRIM VALVE FAULT DURING BITE. PERFORMED CABIN TEMP CONTROL AND INDICATION OPERATIONAL TEST, REF B737-800 AMM 21-61-00. OPERATIONS CHECKS GOOD, NO FAULTS. ETOPS SIGNIFICANT SYSTEM GROUND VERIFICATION SUCCESSFUL.