As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER START CHECKLIST, THE LEFT PACK LIGHT ILLUMINATED, MC RECALL. EXTINGUISHES WITH MC RESET. ACFT GROUNDED. PERFORMED CABIN TEMP CONTROLLER BITE IAW FIM 21-61-00-810-801, FLIGHT DECK TRIM VALVE FAILED ON ZONE TEMP CONT 2. REMOVED AND REPLACED THE ZONE TRIM AIR MODULATING VALVE IAW AMM 21-61-21/401, BITE TEST PASSED. NO LEAKS.