If your temp gauge is to the 1/2 way mark, check to see if the radiator fan is on.If not ,turn a/c on if equipped. If then the fan comes on, most likely have a bad temp sensor/switch in your thermostat housing. Find the connector to the switch on thermo housing. Unplug and short the connector. Do this when you know the engine is running hotter than it should. If your fan comes on when you short the connector, than your temp switch is bad.