The combustion fan starts really slow and laboring while it builds up steam until it is running full speed. That just doesn't sound right to me. shouldn't it just start off full speed. Also some times(not always) it sounds like a small explosion (pop) when the furnace lights. Kind of like your barbecue when the gas is on to long before you hit the ignitor. I have not looked at it to see if flames come out the side like you see on your barbecue when you lite it late.
Ideas?