What was found
AIRCRAFT WAS GROUNDED: ON DESCENT THROUGH 12000 AN ACRID SMELL IN THE FLIGHT DECK. THEN AT 2000 FEET BEFORE ENTERING THE CLOUD DECK THERE WAS A MUSTY SMELL IN THE FLIGHT DECK. MAINTENANCE FOUND THE APU COOLER VENT LINE AND THE APU GEARBOX VENT ORFICE CLOGGED AND REPLACED THE VENT LINE PER AMM 49-52-51 (AALA202502066739) AND THE ORFICE PER AMM 49-26-55. (AALA202502068410) THE APU OIL COOLING FAN WAS CONTAMINATED WITH OIL AND WAS REPLACED PER IT AMM 49-52-51. (AALA202502068925). A DECONTAMINATION OF THE ENVIRIONMENTAL CONTROL SYSTEM WAS ACCOMPLISHED PER TASK 26L00021014. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO LEAKS OR ODORS NOTED.