turned off, motor keeps running for? As I am driving, a sound (as if heater or air conditioner is on when its not), then when vehicle is turned off, this "sound" continues coming from the back of the vehicle until I put the key back in, turn it as if I'm turning on the car, and the noise will stop. Sometimes it keeps going again and I have to reinsert the key again and then it'll stop. What's this?