Our home was built in 2002 and the furnace wasn't working right in 2004 so we called the repairman.He came and told us that he would have to order a part and that he wired it so the fan would blow continuously until the part arrived.He never came back and our furnace has been blowing ever since.Does anyone know which part he would be talking about? The furnace is a Goodman/Janitrol A42-20. I'd like to save some money and order the part myself and install it. Thanks.