I have a mercedes benz c class 200 and need to know how to replace the heater blower resistor thanks yolande

The heater blower motor is located outside under the front scuttle panel, the plastic are where the wipers bolt on. You should extend the bonnet to its horizontal position, remove the wiper arms, then carefully remove the rubber seal and plastic scuttle panel trim.Some edges are sharp so be careful. Be careful not to loose any clips or rubber seals. You will see the blower motor now. Make sure the ignition is off and you have the key as someone could accidentally operate the wipers or the heater blower, the former can take your fingers off. Anyway the resistor is under the motor, unplug it and remove. Refitting it a reversal of the above.If you ever have to remove the wiper motor arm from its spindle ensure you index mark it first !