As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN HAS AN ACRID ODOR WITH NOTHING RUNNING. STARTED APU AND ODOR INCREASED WITH BLEED AIR ON. STARTED ENGINES AND SHUTDOWN APU. ODOR WAS SLIGHTLY PRESENT. CLEANED DUCT. CLEANED COALESOR UNIT. INSTALLED COALESOR UNIT WITH NEW AND RAN APU FOR 45 MINUTES. OPS CHECKED NORMAL IAW MM 21-50-00.