As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BAD SMELL IN AC SYS. IT IS NOTICEABLE WITH APU BLEED AND ENGINE BLEED. IT IS WORSE AT LOW ALTITUDES, WHETHER ON CLIMB OR DESCENT. AT CRUISE SMELL SEEMS WORSE IN BACK. ON FINAL APPROACH PASSENGER AND F/A IN BACK OF ACFT WERE COUGHING AND COMPLAINING OF SMELL. REPLACED LT AND RT CATALYTIC CONVERTERS, NO SMELL NOTED.