As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MIA - INFLIGHT T2031/15, ON DESCENT PASSING 10000 SMOKE IN COCKPIT. DISAPPATED AND RETURNED AT 6000. SMELLED ACRID ELECTRICAL SMELL. WENT ON OXYGEN AND LANDED. SMOKE WENT AWAY. SMOKE WAS VISIBLE IN COCKPIT DURING EVENT. REPLACED LOWER RECIRCULATION FAN. SYSTEM GROUND CHECKED NORMAL OPERATION.