AIR CONDITIONING SYSTEM CAUGHT ON FIRE, BLOWING FLAMES FROM BURNING PLASTIC INTO PASSENGER COMPARTMENT, WHILE DRIVING ON RESIDENTIAL STREET W/ AC ON. PROBLEM DIAGNOSED AS LEAVES CRUMBLING THEN FALLING THROUGH AREA WHERE WINDSHIELD WIPERS SIT INTO THE AC BLOWER INTAKE, THEN SITTING IN THE BLOWER. RESISTOR SITS NEXT TO BLOWER, GETS "ALMOST RED-HOT" WHEN AC IS ON; THE HEAT IGNITED THE LEAVES IN THE BLOWER, THE PLASTIC CAUGHT ON FIRE, AND FUMES FROM LEAVES AND BURNING AC SYSTEM WERE BLOWN INTO PASSENGER COMPARTMENT. THE SHOP (ALBANY HILL AUTO) SAID THE BLOWER SHOULD HAVE HAD A GRATE OVER THE INTAKE TO KEEP LEAVES OUT AND THE INTAKE WAS POORLY POSITIONED TO BEGIN WITH.*AK