Sometimes it will go on during cruising when I was in the summer . Its off and on really. Just did it yesterday. So I texted a few of the gurus I know and they said replace fan delay relay. Or we will see if its sticking. You have me doubting myself now haha. I really couldn't tell you how hot as no temp lights or anything of that nature. Sometimes it will go on and shut off right away sometimes it doesn't. I just don't want to burn out the fan.