I have no check engine lights on or any warning lights on. also defrost and AC are both off and the fans still run. i also noticed that there is a sensor on my rad (i assume a level sensor) could this be the problem? does anyone now how to check if that sensor is working? (resistance value for sensor) i don't want to have to change it if i don't have to (i can't afford to keep replacing parts that are fine) or if you can even change it or do you have to change the whole rad?