I have a Bryant Central Heat Air system. Recently my drain pan clogged and began to over flow in my loft. After discovering and removing water in the drain pan, I noticed my unit was working but wouldn't cool because the furnace wouldn't shut off. The heat was running the same time as the AC. I suspect one of two possibilities: mother board or furnace controller. Can the furnace be by-passed? If so how? Also is it difficult to swap-out the motherboard?