As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MCO - FLT 1857 EN-ROUTE CLT TO MCO. AFTER ENG SHUT DOWN AT THE GATE THERE WAS A PUNGENT ODOR LIKE BURNT MATTRESS IN FIRST CLASS AND REST OF CABIN. TWENTY MINUTES FROM MCO HAZE AND ODOR, TURNED OF RECERC AND HAZE WENT AWAY. PERFORMED VISUAL INSPECTION OF APU DUCTS. NO OIL NOTED. RIGHT RECIRCULATION FAN WAS PLACED ON MEL. MAINTENANCE REPLACED THE RIGHT RECIRCULATION FAN. SYSTEM CHECKS OK.