While driving and operating the heater, unbeknowst to me leaves/pine needles had come in through the fresh air cowl vent and built up on the heater blower resistor resulting in a fire. This design in dangerous as the default for the air intake is open and allows debris to enter and drop directly into the fan and blower motor resistor. I've searched online and seen multiple reports of this issue. I have a video I can provide if contacted.