As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, THE CREW REPORTED SMOKE IN THE CABIN AND ELECTED TO RETURN TO DEPARTURE WHERE THE AIRCRAFT LANDED WITHOUT INCIDENT. UPON INSPECTION, MX FOUND THE SOURCE OF THE SMOKE TO BE A SEIZED NR 1 AIR CYCLE MACHINE (ACM). MX REPLACED THE ACM, PERFORMED OPS CHECKS AND CLEARED THE DISCREPANCY.