Thermister location on a 328

What in the hell is a Thermister?

 

It sounds to me like you are talking about what I call a "temperature sending unit". That unit on a 308 anyway is on the lower side of the radiator on the passenger side. It has a harness with two wires connecting to it. On my car it is also the only way to drain the radiator.

 

The temperature switch on the radiator controls the electric fans. Another switch on the coolent reservoir (aft) is for the CIS loop control.

The thermistor that runs the gauge is on the coolent manifold (from the upper water pump pipe) for coolent to the heads that sits under the intake manifold plenum, on top of the engine. The wiring doesn't go anywhere near the radiator.

 

Clever!

 

?? - Wiring diagram and spare parts catalog.
(And 3-1/2 decades experience with Italian cars ... which is why the first thing I buy after the car is all the manuals I can get. )

 

Well the thermister is a new one on me. Thank god for this informed forum.

 

Not discounting your knowledge/experience in anyway...thought you were being clever by your choice of words given the thread topic.

 

Proper spelling is thermistor. That's obviously what threw you.
Thermocouples work well for wide temperature variations, are cheap, but are difficult to calibrate and stay calibrated. They are dissimiliar metals and like a small battery which produces a voltage which varies with temperature.

Thermistors are temperature sensitive resistors. They have a large output variation for smaller temperature ranges, are exceptionally stable over time and inherently more accurate. But they do require special meter circuitry to avoid car battery voltage variation from affecting the reading.

Nothing but the best...

 

Nah -- the temperature switches are off/on switches, and the gauge sender really does show as a thermistor on the wiring diagram.

One of my ongoing projects (suspended for lack of time now) is a thermistor based aircon thermostat to replace that Coke-machine capillary tube unit. (You have to remove half the interior to replace one of the capillary units.) It uses one unit of a quad op-amp as a constant current source, run across a radio shack thermistor (in parallel with a fixed resistor) to eliminate voltage variations and non-linearity of the thermistor output.

(The other units scale the output, compare a potentiometer setting, and drive the switching transistors to push the relay. -- The first prototype failed because those Bosch relays pull a heluva lot more current than I expected. I also realized that radio shack (non mil-spec) parts wouldn't last long inside the console, so the electronics have to be relocated to the evaporator -- where Ferrari put the fan speed transistor.)