Not to hijack, but I have been noticing while I am idling in traffic, my fan isn't kicking on when it usually does, around the OR range. But if I pull in my driveway and put it into park and let it idle, when it gets to that range the fan kicks in. I am thinking either sending unit or themorstat. The thermostat was just replaced last summer, but maybe this one is sticking. Any suggestions? Oh the water pump was replaced last summer as well and I have heat so I know it isn't that. TIA!!