I just bought a 99 wagon with 108k miles. I was a great deal. But the coolant low light is on the dash stays lite. But the coolant if full and when driving the temperature stays below 1/2 way. 24V engine

Welcome to the forum. There is a sensor in the coolant reservoir that may have gone bad. If coolant level is not dropping, look at the sensor.

ford has an updated coolant de-gas bottle for the taurus line for this concern. comes with the new level sender and float for this concern.