The temperature control is not set to any measured temperatures, but merely has an unmarked analogue dial similar to an electric radiator thermostat.
Since there are no wires to a thermistor or similar in the hot-end, and the dial ‘clicks’ on at the lowest point of the dial, an educated guess is that this controller uses some kind of PWM to drive a power level determined by the position of that dial on a potentiometer. Hence no temperature markings, as the resulting tip temperature will depend on environmental conditions.
