The fan in your car stopped working except when set to the highest setting.
Car heater fan only runs on high.
If it doesn t light up or you only have a high fan speed then your resistor block needs replacement since it is bypassed on high speed.
Though having only one fan speed usually indicates a bad blower resistor a diligent mechanic at a repair shop will test the resistor fan switch and connections to the motor to make sure nothing.
If the resistor block tests out good and you don t have any fan speed or a slow fan speed for all speeds you can assume that the blower motor is at fault since everything else has tested out ok.