Brrrrrrr. Sounds like it's cold in your Passport when you drive around. I keep mine at 70 year round.It will also turn off automatically if your temperature is set to LO. Even if the fan is off, I've noticed that the auto idle doesn't turn on as long as the original temp setting was LO. I was trying to opposite and get it to turn on and couldn't figure out why it wasn't turning on until I raised the temperature by 1 degree to 58. Idle on started again.