As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DESCENT TO 21000 FT, MAIN DUCT TEMP ROSE TO 120 DEGREES. GOT TEMP BACK TO 80 DEGREES. F/A NOTIFIED CREW SMOKE IN CABIN. BY THE TIME ACFT WAS ON THE GROUND SMOKE HAD DISSIPATED. REPLACED COALESCER BAGS, RAN ENGINES. UNABLE TO DUPLICATE.