earld

I have a 99 slk230 with a bad blower resistor. I want to replace it but have read that if I buy a OEM resistor it may be one thatis the newer version and a blower motor replacement may be necessary . Is this true in my case or do I just change the resistor? Any one got a picture of its location? Or directions. I know its under the dash on passenger side but how much of the stuff do I need to remove to get to it?
Sorry to sound so stupid but I have not done this before and I just need to know what I am getting myself into. I dont want to spend all day upside down in the car. Thanks