I have a ICP furnace model FBF075B12A
My problem is the fan run at all times and won't shut off I was wondering if I need to replace the whole control board which is a honeywell ST9120C 4040 or some other part.

Does the furnace work? Probably not. If it is the main blower you are talking about, it probably is a limit switch. If this is the case, there are a few things that need to be looked at. Limit switch are to keep the furnace from overheating, could be caused from dirty filters, blocked duct, etc.