What was found
ON DESCENT, AT APPROX 17,000 FT, AN ACRID BURNING ODOR BEGAN IN CABIN AT SEAT ROWS 5 AND 6, ODOR SPREAD THRU CABIN AND INTO COCKPIT. TURNED GASPER FAN OFF AND BOTH PACKS TO FULL COLD, ODOR DIMINISHED BUT STILL LINGERED. FLT ATTENDANT PULLED ALL CIRCUIT BREAKERS IN BOTH GALLEYS AS PRECAUTION. MAINT TROUBLESHOT & ISOLATED PROBLEM TO PASSENGER CABIN A/C FAN, REMOVED AND REPLACED CABIN AIR FAN IAW BMM 21-24-21. RESET GALLEY CIRCUIT BREAKERS, OPERATIONAL CHECK OF GALLEY AND CABIN AIR FAN WAS GOOD. VENDOR FUNCTIONAL TEST OF CABIN AIR (GASPER FAN) S/N AA-39653 CONFIRMED FAILURE OF UNIT. FAN WAS FOUND TO BE VERY NOISY AND HAD ONE PHASE OUT.