ok, here's the deal. we got this car about a month ago. everything was fine. at the beginning of the week a light came on in the panel showing a radiator and a temp gauge. ok, so i look at the temperature indicator and the temperature was fine. it was below the halfway mark. i pulled over and looked under the hood and there was a sufficient amount of antifreeze in the coolant box. and on saturns there is not a radiator cap on the actual radiator, there is just a cap on the coolant box. the temperature never got up so i just forgot all about it. ok, yesterday we were driving in town and i notice that the temperature was coming up over the halfway mark. we came home and it was dark i lifted the hood and i didn't have a flashlight so i couldn't tell if the fan was running. so today i go to town and the same thing happens. i return home and the temp. guage was above halfway and the lights on the panel flashed. it was daylight so i lifted the hood and i looked and the fan was not on.
also the air conditioner usually runs cold, but today it was not cold and then it was and then it wasn't. i dont know if that has anything to do with it or not.

if the a/c is intermittant,
i'd check the belt,as it drives your water pump also...

If the car's temp is fine and the coolant isn't low, it's probably a defective sensor. Take it to Pep Boys and they can run the diagnostic machine on it for under $20.