As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH THE LT ENGINE AND THE APU RUNNING, AFTER RT ENGINE START, HOT AIR WAS BLOWING OUT OF THE VENTS WITH THE TEMPERATURE CONTROLLER ON FULL COLD. STARTED TO GET SMOKE IN THE CABIN ON TAXI OUT. R & R AIR CONDITIONING PACK COOLING TURBINE. LEAK AND OPS CHECKED GOOD IAW MM 21-51-00.