Contour temp unsteady

I took delivery of my contour yesterday...it drives nice...only issue seems to be the temperature. When I first picked it up, city driving the temp hovered around the halfway point or a little over the halfway point, then got out on the highway for the 2 hour trip home and within the first 30 minutes of the trip, the temp gauge dropped to almost cold. It was slightly before the "N" in the word normal. The coolant light is not on, but the check engine light is. the previous owner says he replaced the waterpump already. It is the 2.5 V-6 engine.

They probably didn't replace the thermostat when they did the waterpump.

They probably didn't replace the thermostat when they did the waterpump.

Ok, well fast forward several weeks. Now it gets warm outside and I start to run the A/C, not the contour runs hot. several days on the way to work I had to run with the heat on to lower the engine temp or it would have gone into the red. i had the radiator flushed, thermostat replaced, water pump belt replaced, but it still runs hot. i plan to replace the water pump tomrorow. What else might it be beisdes what I mentioned?!

You may wanna look at the cooling fans, to make sure they are coming on, and check the coolant temp. sensor, its the sensor right on top of the thermostat housing.