As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THE LEFT PACK BLOWING SMOKE ON FLIGHT DECK. MAINTENANCE INSPECTED AND DEFERRED THE LEFT HAND AIR CONDITIONING PACK PER MEL 21-51-01. MAINTENANCE REMOVED AND REPLACED THE PRESSURE REGULATING VALVE IN ACCORDANCE WITH THE AIRCRAFT MAINTENANCE MANUAL. AIRCRAFT WAS RELEASED FOR SERVICE.