What was found
FLT#1510, PUJ-FLL. 'APU OFF- STRONG ACRID / BURNING OIL/DIRTY SOCK TOXIC FUMES THROUGHOUT AIRCRAFT WITH STRONGEST SMELL IN COCPIT. DESCENT PHASE BELOW 10,000' FROM PACKS, AND PRESENT UNTIL LANDING. USING COCKPIT/CABIN ODOR RECOGNITION AND ISOLATION CHECKLIST- UNABLE TO ISOLATE SOURCE TO PACK 1 OR PACK 2; FOUND APU OIL COOLING FAN TO BE THE SOURCE OF ODOR CONTAMINATION, REF LOG PAGE 3688568-1 FOR APU DEFERRAL. "COMPLIED WITH INFO NOTICE 2017-T015J, SECTION B2. DECONTAMINATION LEVEL B WAS ACCOMPLISHED PER TSM 05-50-00-810-831-A. A/C IS OK FOR SERVICE. REMOVED AND REPLACED RECIRC FILTERS IAW AMM: 21-21-41 AS PRECAUTION.'