As you probably know, many things designed for "mobile home" are odd balls. They don't have to comply with the same codes as houses, and for obvious reasons are made with "compact" features. You really need the manual and wiring diagram for the furnace, which you might find under a cover. The furnace may have the option to bypass the internal fan and H/C switches, and externally wire those functions. You have to find out how to wire that. At this point, you apparently have two wires to the furnace. That will NOT control fan and H/C, so you need more wires and you need to know how to wire the furnace. Look for that manual and diagram.