my ac blower motor blow at low speed lateley on 1997 Mercedes-Benz E320

The blower motor just start to blow at low speed i beleave it the blower resistor what should it cost to repair this problem

usually the resistor burns out it only works on high
1 more answer , 1 more comment
I would guess it to be the fan speed regulator. My records indicate 9 out of 10 times when it's low speed only, I've replaced the regulator for a proper repair. Be sure to check the current draw on the blower motor as it may be high creating undo stress on that particular circuit.

is this a big job and does it cost a lot to fix, my fan only blows on the low speeds Thanks