As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AC HAD DEPARTED THE GATE AND WAS TAXIING TO RUNWAY FOR DEPARTURE. SEVERAL MINUTES AFTER ACTIVATION OF THE LT AND RT AIR CONDITIONING SYS. SMOKE WAS NOTED IN THE CABIN AND COCKPIT. THE SMOKE WAS ISOLATED BY TROUBLESHOOTING TO THE LT AIR CONDITIONER. THE AC RETURNED TO THE GATE AND MAINTENANCE VERIFIED THE LT AIR CONDITIONING COOLING TURBINE WAS SEIZED. THE AFFECTED COOLING TURBINE WAS REMOVED AND REPLACED. (K)