Q: Car overheating - 1999 Nissan Sentra

This may be a sign of a faulty coolant fan relay. This relay receives input from the coolant temperature sensor which reads the temperature of the coolant in your radiator. As it reaches a certain temperature, the cooling fan relay receives a signal to turn the fans on to help cool down the coolant flowing through the radiator. When your car is moving down the road, the coolant is also cooled down simply by wind passing through the radiator. When it is sitting still, without the help of the wind when the fan is not working properly, it may overheat as you have experienced. I would recommend having an expert from YourMechanic come to your location to diagnose the cooling system so that this can be addressed appropriately.