Is there a special tool to use? Do I go through the dash board? Will I have to be careful of my airbags?

I don't have specs for the 190d but I have the C230 model 170 which should be similar. I have attached instructions and a diagram to help you. You should not need any special tools, just dis-connect the battery first.

I can't really get a good picture of the diagram. My heater quick working, will replacing the heater blow fan help or could it be a sensor? If it is a sensor, where do you go to replace the sensor ? or switch? My cigerate lighter stop working, where is the fuse to replace the one that is blown out?

I am attaching another diagram which shows control sensr. You should be able to click on picture to get full size view. The fuse box is either under the drivers side kick panel, behind the glove box or in trunk if you have trunk mounted battery.