Heater blower only works on level 4

I can only talk in general terms, my US automotive database won't have any wiring diagrams for your vehicle. When the problem is ongoing, I'd check voltage and ground at the blower motor wiring connector, If good voltage and ground with no blower action, suspect the blower motor is faulty. If the blower motor has brushes, if the brushes get worn, sometimes you can tap on the blower motor or hit a bump going down the road and the blower motor may start running? Hi speed doesn't usually use a resistor.