What Is a Car Radiator Fan?

What Is a Car Radiator Fan?

Your car’s radiator fan plays an important role in regulating engine temperature. It disperses heat picked up by coolant as it passes through the radiator.

If you hear a whirring noise or notice that your engine’s coolant is low, it could be a sign that the radiator fan has stopped working. Here’s how to check the problem:


There are two types of car radiator fans: mechanical and electric. Mechanical fan blades connect to a pulley and are rotated by engine rpm. These types of fans are usually used on older cars. Electric fans connect directly to the car battery and do not require the engine to be running. These fans are more compact and can be switched on and off with sensors and an ECU.

These fans push air from the front of the car towards the radiator and the engine block. These fans are car radiator fan often rated by the amount of airflow they can deliver, which is measured in cubic feet per minute (cfm). The best way to determine a suitable fan is to measure the maximum cooling demand of your engine.

Typically, customers choose between a straight or curved fan blade design. The straight blades are able to move more air, but are noisier. The curved blades tend to be quieter, but are less effective at moving air. In general, a straight blade is better suited to street use because it can move more air and cool the engine faster. In addition, a straight blade is more durable and will not bend or break as easily as a curved blade. Whether a customer chooses a straight or curved blade, they should look for a high-quality replacement fan motor. This is the most commonly broken part on a radiator fan and should be replaced as soon as possible.


The cooling fan takes away heat that the engine absorbs when it runs. It moves air over the radiator and also through other coolers like the A/C compressor, transmission fluid cooler and power steering fluid cooler. It only runs when the car isn’t moving fast enough for natural airflow to cool the engine.

The motor in the fan can be either a solid-state or electric model. The solid-state type is the most common on older cars. It’s simple and robust but lacks the ability to turn on and off as needed. Electric fans offer the advantage of control, which they accomplish with a complex system of relays, fuses and connectors or wires. Modern electric fans are often triggered to power up by temperature sensors, which make them more efficient than their mechanical counterparts.

Radiator fans can be straight or curved and they can have as few or as many blades. Generally, more blades result in better airflow. Straight fan blades tend to be louder but are capable of moving more air than curved models, which are quieter but may not move as much.

The shroud that covers the fan can be made of plastic or metal. Many OEM fans have trap doors installed that stay closed at low speeds to prevent bypass and open at high speeds to increase air flow through the cowling. This increases the pressure differential over the fan and allows it to pull air in rather than push it out, which is more efficient.


When a car radiator fan gets loud it can be a major nuisance. If the noise sounds like a plane priming for takeoff or drowns out conversations anywhere near it then there’s probably something wrong with your fan. The louder your car’s cooling fan is the more stress it puts on other components such as the engine which can result in decreased performance and possibly overheating.

There are several things that can cause a radiator fan to be louder than normal. For example, the blades could be bent or damaged which causes them to rub against the housing or shroud. This usually happens over time as the fan comes into contact with debris and other objects. It’s also possible that a rattling sound is caused by loose screws or bolts which can make the fan vibrate in its mounting system.

Another possibility is that the radiator core or carrier bags are blocked by dirt, sand or leaves which causes the fan to work harder to cool the car radiator fan engine. Lastly, the fan clutch may be wearing out and making a rattling sound when it’s activated.

The best way to determine if your radiator fan is working properly is to pop the hood of your vehicle and locate it. If it’s working as it should then there shouldn’t be any strange noises coming from underneath the hood. If there is, it might be a good idea to visit one of the 17,000 NAPA AutoCare locations in your area.


Radiator fans are rated by the amount of air they can move in a minute (cfm). When selecting a fan, make sure you have the CFM rating that matches your engine size. Using an incorrect radiator fan can cause overheating, which may lead to costly repairs and even engine replacement.

The radiator fan moves air through the radiator and the A/C condenser to remove heat from them. In most cars, the fan only comes on when cruising at low speeds to keep up with air pressure differences caused by vehicle motion. The engine coolant temperature sensor sends a signal to the fan to turn on, based on the coolant temperature reading. If the sensor fails, the fan won’t come on and you’ll experience overheating problems.

Most modern cars use a single radiator fan assembly with an electric motor to cool the engine. In some cases, especially with larger engines or modified ones that require more air to take away the heat they produce, a dual fan assembly is used.

Another thing to consider is the type of fan you want, which can be either pusher or puller. Pusher-style fans mount on the front of the radiator and push air through it, whereas puller fans mount on the back and draw air. The fan shroud can also affect airflow, with a larger one providing better cooling.

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