The temperature gauge is fluctuating into the high temp area when the car is idling or in stop/go traffic. When I drive, the temp cools down. I've installed a new thermostat and performed a radiator flush and refill. Looking under the hood at idle, the radiator cooling fan does NOT come on as the engine temp increases, but DOES come on after I turn the ignition off. Are we talking a faulty temperature coolant sensor here? Why does the fan come on only after the engine is off?
IMPORTANT: The fan DOES operate (along with the compressor fan) when the A/C is turned on, and that seem to cool the engine down.