As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RECEIVED L PACK AUTOFAIL CAUTION ARRIVING TO GATE. DURING THE FLIGHT HAD LIGHT SMOKE AND ASH FROM AIR VENTS. REPLACED ACM IAW JOBCARD 900-21-310-902. ALSO REPLACED THE TEMP CONTROL VALVE AND PACK SENSOR AND REPLACED O-RINGS FOR THE DUCT TO THE HEAT EXCHANGER IAW AMM 21-51-08. NO LEAKS NOTED. ALL OPS CHECK GOOD.