I think that it's my fan as well. I have not heard it kick on. I know it's not the thermostat cause I have already replaced that as well. How would I know what exactly waws wrong with the fan. What I mean is how do I know if it's the fan itself, wiring, or the fuse. Or would I be better off replacing all of it? Also, would that be why the fluid in my overflow tank is boiling?