A radiator fan motor is an important component of your vehicle’s engine cooling system. It is part of a larger assembly that includes the motor, fan blade, and a housing or shroud. The radiator fan assembly, also known as a cooling fan assembly, is mounted directly behind the radiator in the engine compartment at the front of your vehicle.
As a result of the combustion process and friction from the moving parts inside, an engine gets hot quickly. In order to prevent overheating, liquid coolant (“antifreeze”) is circulated through the engine block where it picks up some of the heat. The coolant is pumped out of the engine through rubber hoses to the radiator. There inside the radiator, the coolant flows through a series of small tubes, transferring heat to the tubes along the way. The heat is passed on to a matrix of wafer-thin aluminum cooling fins attached to the tubes, and air passing through the radiator allows that heat to dissipate into the atmosphere.
The radiator fan helps to draw air through the radiator to help in this process, especially when your vehicle is standing still. Some engines, especially older models, feature engine-mounted cooling fans. Most modern vehicles have electric radiator fan assemblies, each with a radiator fan motor at its core.
There was a time when radiator cooling fans were attached to the engine and driven by a pulley. With that mechanical arrangement, it was easy to see whether the fan was spinning or not. In most cases, that is no longer true. Instead, a modern radiator fan is driven by an electric motor that can cycle on and off as your engine heats up or cools down. But because the fan does not run continually, it is difficult to diagnose by merely observing whether or not it is running.
If your radiator fan does not engage at all, no matter what the temperature gauge on your dashboard reads, then the fan motor might be bad. Certainly, if your engine overheats and the fan fails to come on, the fan motor could be the culprit. Steam coming from under your hood might be a sign of overheating, as might be a cooling system warning light or even the check engine light. A blown fuse in the radiator fan motor electrical circuit might also reveal a bad fan motor.
Unfortunately, these signs can also point to other issues besides a bad radiator fan motor, such as a failed fan relay or damaged wiring. It is important to have the problem properly diagnosed in order to avoid engine overheating and significant engine damage.
An electric radiator fan assembly is mounted in the engine compartment directly behind the radiator. To replace the assembly, a technician will disconnect the battery, taking care to preserve the vehicle computer memory. Shields, covers, or other components that are in the way of access to the fan assembly must be removed as well.
While the process can be a bit different depending on your vehicle make and model, other steps a technician will generally take to replace the radiator fan motor include unplugging the fan motor from the wiring harness, locating and removing all of the fasteners that hold the housing or shroud in place, and pulling the fan assembly from the vehicle.
With the assembly out of the vehicle, the technician will remove the fan blade from the motor and the motor from the shroud. A new fan motor is inserted and the blade is reinstalled before the entire assembly is placed back into its mounting location. Once the assembly is fastened in place and plugged back in, the technician will replace all other components that were removed for access. Lastly, the technician will run your engine to ensure that the fan works as it should.
In some cases, it will make sense to replace not just the motor but the entire radiator fan assembly. The recommendation to do so might come down to the cost of the new assembly versus the cost of overhauling the old one.