Where is the engine coolant temperature sensor located?

The car listed above is a limited Edition. It started to blow only cold air and overheat at the same time messed with the controls inside on the dash and it randomly started blowing hot air and the engine cooled off. Strange right? 15,000 miles later it started this again only overheating at a constant, so I changed the thermostat, the water pump, the radiator, flushed the heater core (water flow freely), changed the cabin filter, and now I'm stuck. Randomly though the heat will start to work and then the engine stays cool but that only lasts a moment. There are no leaks anywhere except when it overheats and goes out the overflow that's it. So, I'm exploring any other option I can find.