What was found
UNIDENTIFIED ENVIROMENTAL SYSTEM ODOR BEGAN ENTERING THE CABIN PASSING 7000 FT WITH THE THROTTLES NEAR IDLE IN DESCENT. VISUALLY INSPECTED RT AND LT ENGINE INTAKE AND EXHAUST, NO DISCREPANCIES WERE NOTED. GAINED ACCESS TO THE REFRIGERATION UNIT AND VISUALLY INSPECTED, NO DISCREPANCIES WERE NOTED. OPERATED LT AND RT ENGINES AND ACCOMPLISHED REFRIGERATION UNIT OPERATIONAL CHECK TWO SEPARATE TIMES AT 1/2 HOUR EACH, SWITCHED PRESSURE SOURCE FROM LT RNGINE TO RT ENGINE AND NO UNUSUAL ODERS WERE NOTED IN THE COCKPIT OR CABIN. OPERATIONAL CHECK WAS FOUND TO BE SATISFACTORY. NO DISCREPANCY WAS NOTED AT THIS TIME. REINSTALLED REMOVED PANELS TO GAIN ACCESS. ACCOMPLISHED IAW HAWKER 400XP MM 21-50-00.