What was found
AFTER TAKEOFF FROM CLT, AIR CONDITIONING HAS A STRONG DIRTY SOCK/OILY SMELL. ODOR SEEMED TO SUBSIDE SOME BUT WAS STILL THERE AFTER TURNING OFF HIGH PACK. FLIGHT CONTINUED AND LANDED AT EWR WITHOUT FURTHER INCIDENT. MAINTENANCE ACCOMPLISHED J/C 03L00021001 AND FOUND APU TO BE AT FAULT. APU REQUIRES FURTHER TROUBLESHOOTING TO DETERMINE WHAT IS CAUSING ODOR. APU PLACED ON MEL 49-01A. FURTHER TROUBLESHOOTING REVEALED NO LEAKS AT APU. OIL SERVICED TO PROPER LEVEL. REMOVED APU LOAD CONTROL VALVE AND FOUND NO EVIDENCE OF OIL RESIDUE IN DUCT. ACCOMPLISHED J/C (OIL SMELL/SMOKE IN CABIN) 03L10025001. NO DISCREPANCIES NOTED. RAN BOTH PACKS ON APU, THEN ENGINES. NO ODOR PRESENT. REMOVED MEL 49-01A. AIRCRAFT OK FOR SERVICE.