You tried turning on the ac and the different climate controls and it s the same.
Car heater fan only runs on high.
My heater and ac fan only works on high when i turn my switch on for the fan on the heater and ac it only works on full blast.
The fan in your car stopped working except when set to the highest setting.
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.