I thought I would create a new thread that gets straight to the point for new comers. Will the TMS operate when the Volt is not plugged in to cool or heat the battery depending on temperature? I was watching the temperature video on the Chevrolet website and it stated "When the outside is scorching hot the Volts battery needs cooling so it automatically uses some of its electric power to cool the battery but you may experience a little less EV range". This is when the Volt is being driven but does not mention anything about the TMS operation if it works when the vehicle is parked in a hot or cold parking lot and not plugged in. Maybe someone can clear this up if the TMS will or will not work if its not plugged in.