As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI OUT A WHINING NOISE WAS HEARD AND A BURNING SMELL FILLED CABIN. RETURNED TO GATE AND FOUND THE CABIN AIR RECIRCULATION FAN CIRCUIT BREAKER HAD OPENED. CIRCUIT BREAKER WAS COLLARED AND SYSTEM WAS PLACED ON MEL 21-31-C1, RECIRCULATION FAN INOPERATIVE. MAINTENANCE AT PHX REMOVED AND REPLACED THE CABIN AIR RECIRCULATION FAN IAW BMM 21-21-22, OPERATIONAL CHECK WAS GOOD.