As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DUE TO REPORT OF BLACK SOOT IN CABIN FROM AIR CONDITIONING VENTS ACCOMPLISH PACK OPERATION WITH APU BLEED, FOLLOWED BY PACK OPS WITH ENGINES 1 & 2 BLEEDS TO VERIFY NO SOOT-OIL ODOR NOTED. ENG & APU RUNS OK. RECIRC FILTERS CHANGED. ALL GRILLS ON OVERHEAD BINS NEED TO BE REMOVED AND CLEANED DUE TO HEATER SENDING SOOT INTO ACFT. CLEANED GRILLS ON OVHD BINS AS REQUIRED. OK FOR SERVICE.