As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START CONT CAB ZONE TEMP LIGHT ILLUMINATED WITH MASTER RECALL RESETS OKAY, NO OVERHEAT INDICATED. GROUNDED-YES. PERFORMED PACK/ZONE TEMP CONTROLLER BITE TEST NO CURRENT FAULTS, FOUND FAULT IN HISTORY FOR TRIM VALVE/FLIGHT DECK ON NR 2 CONTROLLER, REF B737-800 AMM 21-61-00--700-806-002. OPERATIONS CHECK GOOD.