Quote:
Originally Posted by Volhv
Is the temperature rating of your thermostat the same as the temperature rating of the fan thermo switch? If not, I think that might be the problem.
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The temp rating of the thermostat is _never_ exactly the same as the fans. The thermostat will be opening/closing all the time while the engine is running, even when the car is moving down the road. It's just that when the car is moving, the movement forces enough air past the radiator to dissipate the heat and there's no need for the fans to be running (in fact, having the fans run when the car is in motion would create turbulence and actually
reduce the airflow over the radiator, at least once you're over about 35 mph). So, engineers don't want the fans to be coming on unless the car is sitting still. So they set the trigger point for the fans higher than the thermostat, slightly higher than the temperature that the radiator is expected to reach when the car is in motion.
Rhett has described the process exactly.
The reason that you don't see the gauge move on more modern vehicles is that modern cars electronically damp the gauge movement. Once the engine is up to operating temp, the ECU on most modern cars just sets the "gauge" to the center and doesn't move the needle unless there is a large swing in temperature.
The 944 gauges, however, just read what the sensor gives them, so they reflect the actual changes in radiator temperature.