As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING TAXI, F/A NOTICED WEIRD ODOR IN THE CABIN WITH BLEED AIR SELECTED OFF. BLEED AIR SELECTED ON AND ODOR INCREASED WITH SUBSEQUENT DUCT TEMPERATURE INCREASE. ACFT RETURNED TO GATE AND SMOKE WAS CONFIRMED IN THE CABIN. NR 2 GROUND COOLING FAN FOUND TO BE NOISY AND INTERMITTENT. GROUND RUN CARRIED OUT AND FAULT CONFIRMED WITH NR 2 GROUND COOLING FAN OFF. FAN SCHEDULED FOR REPLACEMENT. MEL 21-51-3 APPLIED.