What was found
CONT CABIN ZONE TEMP ILLUMINATES WITH MASTER CAUTION RECALL EXTINGUISHES WHEN RESET. GROUNDED-YES. PERFORMED CABIN TEMP CONTROLLER BITE CHECK, FOUND FLT DECK TRIM VALVE FAULT. REMOVED AND REPLACED CONTROL CABIN TRIM MODULATING VALVE, AS REQUIRED, OPERATIONS CHECKS GOOD. LEAK CHECKS GOOD. PERFORMED 2ND BITE CHECK, NO FAULTS NOTED, REF B737-800 AMM 21-61-21-400-801 AND B737-800 FIM 21-61 TASK801.