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Originally Posted by Arthur Dalton
I do not believe that sw is a thermistor sw , but rather just a temp on/off sw.
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I had a 190E many years ago and I think it's a switch; use an ohmmeter and you'll know.
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Originally Posted by Arthur Dalton
The resistor will only work on a thermistor sensor because it changes the resistance of the sensor [with parellel resistance] in relation to temp. This new resistance just puts the sensors values out of spec enough to create an earlier cut-in of the fan circuit. Out of calibration, but to ones own liking. . .
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Calibration is not a proper choice here: The varistors are not calibrated. They are measured as they are manufactured and those that measure within a set tolerance band are ok as usable in the car. That's why some aux fans kick in early (lower temp) that others.
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Originally Posted by Arthur Dalton
An interesting side note to this..
The only reason this resistor bridging will work on these thermistor sensors is b/c the sensors are of the Negative Temp Coefficient design.. meaning , as the temp increases, the resistance decreases.. and when one puts two or more resistors together in parellel, the total resistance also decreases [ei. is always less than any single resistor]. So, you now can change the resistance value of a sensor to have less resistance at a lower temp than the original resistance at that same temp, thereby changing the values of the sensor and allowing for lower temp activation of the fans.
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Not sure what's interesting about that. . . it's been well defined on my web page as that's how it operates. BTW, if a varistor exhibited a postive temp coef, then a parallel resistor would still work. Hint: the operation would be reversed.
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Originally Posted by Arthur Dalton
Many think that this fools the control module , but the control mod just works like it was designed .. it is the upsetting of the relationship of temp/resistance specs of the sensor that have been changed/fooled.
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Again that's how the Cool Harness operates. From the point of the Control Module, it is "fooled". Of course, it's just a figure of speech, don't take it literally as you have done.