OK, you don't believe it is actually overheating. If you want to troubleshoot further you are probably going to need: 1) Some test equipment like a volt-ohm meter; 2)someone needs to tell you what a good temp sensor puts out (like resistance for example) at a specific temperature; 3) An old fashioned mechanical thermometer would also probably help; 4) A variable resistor or variable voltage source (aka a power supply) depending on the info collected under part 2 above.
