I recently did a R&R of the W108. Unfortunately, I did not inspect or test the existing 0.75 ohm & 2.5 ohm resistors inside the heater box.
The blower fan is running at high Rpm's only. The blower motor is 1.5 ohms.
Using Ohms Law, 12v x 25A (fuse at #6) divided by 1.5 = 8A, or 100watts.
So, I will install this Ohmite resistor, in series, after the motor, for a total of 1.5 + 0.7 ohms. This results in 65 watts. I am hoping the result will be a blower motor that runs at 2/3 maximum rpm's, single speed only.
The advise I been given is that the Ohmite resistor will be as warm as a 65 watt light bulb.
Any Electrical guys out there?
http://ourworld.compuserve.com/homepages/Bill_Bowden/ohmslaw.htm