All of the vacuum and sprayer lines transfer to steel pipe in the area of the exhaust manifold. The heat would bake rubber hose. If I recall correctly one tube is for vacuum pump vacuum to the wiper motor and through the firewall into the interior. The second is the vacuum signal from the spray coordinator and the third is the pressurized sprayer hose off the washer bottle. If you're replacing hoses make sure they have raised ribs, denoting that they are vacuum, not pressure hoses. People often use heater hose for the big lines, but they will collapse when hot.