Central Locking

Hi, our 2001 has central locking, it works on passenger side but front and rear doors on drivers side don't work. Looking at the Haynes manual there is a RH front door lock switch - does anyone know if it is located in the door (like the actuator) or elsewhere in the body? The back doors don't have the switch just the actuator (according to Haynes). Any help would be appreciated. Many thanks.