As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNUSUAL ODOR DURING TAXI IN WHEN POWERING APU & THE BLEEDS SWITCH OVER TO APU. ODOR IS SIMILAR TO HOT ELEC EQUIP OR HOT DRYER VENT. R & R NR 1 RECIRCULATION FAN. PERFORMED OPS CHECK OF AIR CONDITIONING SYS WITH APU RUNNING IAW AMM 21-51-00. NO FAULTS NOTED & NO ODORS NOTED.