I don't remember this problem ever coming up before in this forum. Usually you can buy the fan speed selector switch for a Japanese car without replacing the entire climate control unit. The fan speed selector can usually be unscrewed from the main climate control. Maybe someone can track down that part for you (I can't do it on this computer). I never had a need to access the Rodeo climate control, but generally with all cars you can get to the climate control by removing the center counsol and the radio. This gives you access to detach the cables and wires from the climate control so it can be slipped out.

Salvage climate control units may be guaranteed to work, but they can be pretty beat up. I think they take them out with a pry bar. You could always take out the fan speed selector and only use that part.

Pete