Where is the thermostat for the radiator fan on Mazda 323 1985 - 1989?

I believe you are refering to the thermal switch for the electric fan. The switch is located on the bottom tank of the radiator on the driver's side (left-hand drive), just above the drain plug. This switch is a thread-in type with two round prongs where the wires connect. To remove/replace, drain the radiator first, then using a 21 mm socket or wrench, unthreadd the switch from the radiator. There is a second switch which threads into the thermostat housing loacted on the back on the engine head. This switch is part of the emmission control system and also controls the electric fan. Before you remove or replace the radiator switch, disconnect the wire from the thermostat housing switch first, to test the rad switch and electric fan. (I had to do this job just last weekend). Cheers Malcolm