THIS DIESEL TRUCK WAS STARTED IN ORDER TO LET IT WARM UP. OWNER WENT INTO A BUILDING TO RETRIEVE A PAIR OF GLOVES AND RETURNED 5 MIN LATER TO FIND THE VEHICLE ON FIRE. SMOKE WAS POURING OUT OF THE FRONT COWL AT THE BASE OF THE WINDSHIELD. ENTRY TO THE VEHICLE WAS ATTEMPTED IN ORDER TO PUT THE FIRE OUT HOWEVER THE LOCKING MECHANISM KEPT THE DOORS SHUT SO ENTRY COULD NOT BE ATTAINED. THE TRUCK WAS ON FIRE AND IT HAD LOCKED THE DOORS. THE DRIVERS SIDE WINDOW HAD TO BE BUSTED OUT WITH A FIRE EXTINGUISHER IN ORDER TO GAIN ENTRY. ONCE THE FIRE WAS EXTINGUISHED THE PROBLEM AREA WAS EVIDENT. THE ENTIRE HEATER BLOWER AREA WAS MELTED. *TR