I had to clean out my box recently. I has feathers (
) and other debris in mine and when I turned the heat on, smelled like a fire was starting. Best thing I found..I removed the blower motor resistor, then turned on the fan on HIGH. It blows out the bottom where the resistor was. Of these bugs have any weight at all..they will collect down near the blower motor resistor like everything did on mine. Good luck!