When your vehicle’s engine starts running hot, the cooling fan assembly goes into high gear. Its main job is to keep air moving across the radiator so that the coolant can shed heat, especially when your car isn’t going fast enough for airflow to do the work naturally. Without the cooling fan assembly, temperatures can climb quickly, putting your engine at risk of serious and expensive damage.
The cooling fan does its most important work when the engine is running but the vehicle isn’t moving or is moving very slowly.
Airflow through the condenser and radiator at road speed won’t typically require cooling fan operation; the cooling fans are deactivated past a certain road speed on some platforms.
This assembly isn’t a single piece but a combination of the fan, motor, shroud, and sensors that all function together to regulate heat. Modern vehicles typically use electric fans that switch on instantly when sensors pick up rising temperatures or when the air conditioning system needs extra help.
Most front-wheel-drive vehicles have two fans and may run both at half speed (in series) or full speed (parallel) using a special module or a set of PCM controlled relays. Some Jeep Cherokees have a belt driven fan and an electrical fan. The benefit of an electric fan is that it doesn’t put a load on the engine like a belt-driven fan does.
Because of its role in keeping operating temperatures steady, the cooling fan assembly is one of the most important parts of your vehicle’s cooling system.
You’ll find the cooling fan assembly beneath the hood, just behind the radiator. The fan pulls in cooler air from outside the car and pushes it through the radiator fins, lowering the temperature of the coolant that flows inside. When the temperature sensor detects that things are heating up too much, it sends a signal to the motor to fire up the fan.
Electric assemblies can adjust their speed depending on factors like coolant temperature, engine load, or whether the A/C is running. Some older cars and trucks use mechanically driven fans with a clutch that spins in step with the engine. No matter the setup, the goal is the same: prevent overheating when natural airflow isn’t enough, such as when idling in traffic or towing heavy loads.
Usually, the fan is only available as a complete assembly but there are some vehicle platforms where the motor can be replaced, using the same shroud and fan blades. Universal fan motors won’t have a connector and need to be wired so that the fan is pulling air through the radiator rather than pushing air through it unless the fan is an aftermarket fan mounted on the front side.
A complete assembly is made up of several key pieces:
Cooling fans often give warning signs before they fail completely. Here are some of the most common ones:
Fan motors most often fail because their carbon brushes wear down, but dirt, debris, and age all play a role as well.
On average, a fan assembly will last eight to ten years. Its lifespan depends heavily on climate and driving style. For example, cars driven in hot regions or stuck in city traffic most of the time put more strain on the motor. While some fans keep working for the life of the vehicle, it’s common to need a replacement once mileage passes 100,000.
You can, but it’s a gamble. At highway speeds, airflow from the road may keep things cool enough for short stretches. But if you get caught in traffic or drive on a hot day, your engine could overheat quickly. Pushing the car in that state risks warped cylinder heads or even a blown head gasket. The safest option is to replace or repair the rad fan assembly as soon as it fails.
Swapping out a radiator and fan assembly isn’t the most difficult job in the garage, but it does take some care. Here are a few things to keep in mind:
A cooling fan assembly is central to keeping your engine from overheating. Knowing how it works, how long it should last, and the red flags to watch for can save you from breakdowns and costly repairs. If you’re wondering how much to replace a radiator fan costs and do end up replacing one, following basic safety steps makes the process much easier.
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