WHILE PARKED THE BLOWER MOTOR FOR THE CLIMATE SYSTEM CONTINUED TO RUN. THE KEYS WERE REMOVED, ENGINE OFF. UPON DISCOVERY I COULD NOT TURN OFF THE BLOWER. I DECIDED TO TAKE IT TO A SHOP. BEFORE I COULD LEAVE THE PARKING LOT THE CAB WAS FULL OF A THICK WHITE SMOKE. I WAS ABLE TO SHUT THE ENGINE OFF AND DISCONNECT THE BATTERY BEFORE A FIRE STARTED. THE DEALERSHIP SAID IT WAS A COMMON PROBLEM. THERE IS NO RECALL ON IT THOUGH AS THE DEALER IS NOT REPORTING THE OCCURRENCES TO GM SO NOBODY IS AWARE OF THE FREQUENCY. AN EASY INTERNET SEARCH RETURNS MANY OCCURRENCES OF SIMILAR PROBLEMS. *TR