As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START, UPON MASTER CAUTION RECALL, WE GOT "ZONE TEMP" LIGHT ON CONTROL CABIN. GOES AWAY ON RESET. GROUNDED - YES. RELEASED PER ASA MEL 21-21G FLIGHT DECK PRIMARY TEMPERATURE CONTROL INOP. ENROUTE MEL - #2 ZONE TEMP CONT LOGGED 'FLT DECK TRIM VALVE' FAULT, CLEARED AND OPS CKS NML PER B737-900 AMM 21-61-00. GND VERIFICATION SUCCESSFUL. THIS CLEARS MEL 21-21G.