As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE IN THE CABIN SHORTLY AFTER TAKE-OFF. AIRCRAFT RETURNED TO AIRPORT OF ORIGIN. MAINTENANCE DISCOVERED THE CABIN ENVIRONMENTAL CONTROL UNIT MALFUCTIONING. THE CABIN AIR CONDITIONING SYSTEM ONLY PRODUCES HOT AIR AND CAUSES SMOKE TO FORM AND FLOW FROM THE GASPERS AND VENTS. FURTHER TROUBLESHOOTING LEADS TO A FAULTY TURBOCOOLER. THE TURBOCOOLER OIL LEVEL WAS FOUND TO BE LOW AND ALSO OIL RESIDUE IS IN THE SYSTEM AIR PIPES DOWN STREAM OF THE TURBOCOOLER.