As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER PUSHBACK AND STARTING NR 1 ENGINE, THE FLIGHT ATTENDANT REPORTED A BURNING SMELL, (ELECTRICAL OR RUBBER). SHORTLY THEREAFTER, PILOT AND FIRST OFFICER COULD ALSO SMELL IT. MAINTENANCE REMOVED AND REPLACED THE VACUUM GENERATOR IAW AIRBUS MAINTENANCE MANUAL 38-31-64.