Why Does My Car Overheat in Stop-&-Go Traffic? Find Out in the San Francisco Bay Area

If your car is overheating in stop-and-go traffic, but is not doing so on the highway, it's a good indication that there's a problem with the cooling fan. Modern cars are equipped with an electric radiator fan that moves air through the radiator and cools down the antifreeze inside. When traveling at higher speeds, there is enough airflow across the radiator that the fan typically isn't necessary. That's why the engine temperature rises when you're stuck in traffic.

What Could Be Wrong With Your Radiator Cooling Fan?

Older vehicles were equipped with a mechanical fan driven by the engine with a belt. A problem with this type of engine cooling fan typically comes down to the belt or the fan clutch. It's easy to tell if the belt is OK, and the fan clutch can usually be checked by gauging how difficult the fan is to turn by hand when the engine is off. However, modern electric fans are a different story. They're easier to diagnose since you only need to look at it when the engine is running and the vehicle is in Park. Once the engine warms up, the fan will either kick on or not. If it doesn't start spinning, something's wrong.