E-Niro 64kWh '4' since 9/20 (was Prius)
That is normal expected behaviour. However, in light of the known failures of PTC heater elements, IMO its wiser to leave the entire HVAC set to auto and simply adjust the target temperature to your preference. Why would you want to turn the fan speed down? It slows itself down when you reach target temperature anyway . I never ever touch the fan speed knob myself. Full auto climate control takes care of everything automatically.... temperature, humidity, heating, cooling and ventilation.