Maybe they thought they needed to, but since this is a ohm value solution using 12v and voltage dividers, there is no frequency or PWM issues, so I don't see a need. But it probably looks pretty cool. Coax isn't a bad idea since the shielding is used for ground. My variation doesn't require a return ground wire so it would be wasted. If coax isn't used for fuel sending units, it shouldn't be needed here.
The Thermistor is a variable resistor. The control variance is temperature. With the NTC type, Ohm value goes down from the stated value. A 100K Thermistor's ohm value is 100K at room temp and as little as 50K at high temp. It's a really elegant solution for those having trouble trying to figure out how to get a conventional water temp sensor in the water jacket. It also lasts longer because they are not snapping open and closed all the time.
Thanks for the info Mike.. if anyone has any other ideas on what to include in this project... Did we decide that controlling the speed of the fan is probably not a desireable thing?
