What was found
(CAN) AFTER LDG /DURING TAXI TO TERMINAL BLDG CREW NOTICED A SMOKY HAZE IN FWD CABIN& COCKPIT AREA. THEY IMMEDIATELY TURNED OFF LEFT & RIGHT BLEED AIR SWITCHES & THEN ELECTED TO SHUTDOWN ENGINES WHEN THEY DIDN'T SEE ANY NOTICEABLE CHANGE WITH SWITCHES SELECTED OFF.THE CREW & PASSENGERS DEPLANED A/C W/O FURTHER INCID.. MAINT RETURNED A/C TO TH HANGAR & BEGAN AN INSP INTO CAUES OF INCID.. IT WAS DETERMINED THAT LEFT AIR-COND, COOLING TURBINE WAS INOPERATIVE & HAD SEIZED. IT APPEARS THAT BEARING IN THEUNIT IS AT FAULT, RESULTING IN AN IMBALANCE IN ROTATING IMPELLER. THIS RESULTED IN IMPELLER RUBBING ON SHROUD CAUSING IT TO FAIL