As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT THROUGH 12000, A/C PACK OFF MESSAGE ILLUMINATED. BITE CHECK OF ZONE TEMP CONTROLLERS SHOWS LT PACK TEMP CONTROL VALVE FAULTED. WILL NOT CLEAR. REMOVED AND REPLACED LEFT PACK TEMP CONTROL VALVE, INSTALLATION TEST NORMAL. NO LEAKS NOTED.