The fan motor in my 83 240D runs at low speed only. The climate control is manual and no matter which setting on the switch is used, it only runs at the low speed. I've deduced this down to the resistor pack, but this part is NLA and instead of being located on the passenger fender well, it's located inside the evaporator box.

I'm reaching out looking for an alternative. One which I found is using a DC motor controller. They are inexpensive and available, but what characteristics (meaning voltage) should I be looking for ? Top voltage should be 12vdc, but what is the range. Current I know should be less than 15 amps, but there so many options such a brushless, PMW, etc...

I'm sure there are other owners of these cars who have faced the same problem. Is this another viable alternative or is the anything else?

Greg