As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE WAITING FOR A GATE AT DFW WITH BOTH ENGINES RUNNING IT BEGAN TO SMELL SOMETHING BURNING IN CABIN AND COCKPIT. ODOR DISPATCHED WHEN NR 1 RECIRCULATION FAN WAS TURNED OFF. REMOVED AND REPLACED NR 1 RECIRCULATION FAN AS PER JIC 21-22-21. OPS CHECKED GOOD. NO FURTHER DEFECTS NOTED.