Bad Radiator Fan: Symptoms, Causes, and How to Test it

The radiator fan is an important part of the cooling system in a car. It’s placed near the radiator, and its job is to pull in air to cool the radiator and engine. This is really helpful when the car is moving slowly or not at all, as not much air would naturally pass over the radiator fins. By generating this airflow, the cooling fan ensures the normal working temperature of the radiator and engine, even when external conditions aren’t favorable. This article explains the bad radiator fan symptoms, causes, and how to test it.

What is the function of a radiator fan?

The radiator fan, also known as a cooling fan, is one of the major parts of the engine’s cooling system. The main function of the radiator fan is to cool the engine by introducing more air over the radiator, especially when the vehicle is idle or moving slowly. This helps to remove the heat from the coolant circulating through the radiator.

A car’s radiator cooling fan, typically positioned at the front and driven by an electrical motor, is an essential part of the vehicle design. This fan is triggered to operate by two mechanisms in modern engines: an electronic system or a thermostat.

The thermostat, installed between the radiator and the engine, manages the engine’s operating temperature. Simultaneously, the electronic system activates the fan when it detects that the engine’s coolant temperature becomes high.

It’s important to note that this system remains inactive until the engine temperature becomes more than the normal operating temperature or the vehicle remains idle. This fan activates when the thermostat allows the overheated coolant into the radiator. The functionality of the thermostat is critical, as it dictates when the cooling fan should be powered on.

Symptoms Of a Bad Radiator Fan

If your fan is not turning on, it is one of the clear symptoms of a bad radiator cooling fan. A bad cooling fan may also lead to unusual whirring noise, temperature warning light, poor performance of your vehicle’s air conditioning system, or engine overheating.

Let’s discuss the symptoms of a bad radiator fan in detail:

1) Fan is not Turning On

One prevalent sign of a faulty cooling fan relay is the fan failing to activate. This could be due to the electric motor, which works in sync with the fan blades to draw air through the radiator fins, experiencing failure or burnout. Without this electric motor functioning, the fan cannot do its job.

2) Loud Whirring Noise

Occasionally, if the radiator cooling fan motor breaks down, you may hear a pronounced whirring or clicking sound that alters as you turn on the engine.

The radiator fan is a delicate system that operates in sync with the blades. If any part gets dislocated, it could make contact with other parts and cause vibrations.

Moreover, a deteriorating fan clutch may create a noticeable whirring sound. This noise from a malfunctioning radiator fan can be quite loud, but addressing the issue promptly can spare you from costly repair expenses.

3) Temperature Warning Light

An illuminated temperature warning light on your vehicle dashboard is one of the clear symptoms of a bad radiator fan. If this warning light comes on while you’re driving, it’s critical to turn off the vehicle and let it cool down to prevent the engine from overheating.

However, the temperature warning light may illuminate due to many other issues, such as an overheated engine and a faulty radiator. Therefore, when the temperature warning light illuminates, properly inspect the engine and fix the main issue.

4) Poor A/C Performance

If you observe that the radiator fan isn’t operating while the air conditioning (AC) is running, it’s advisable to consult with a mechanic.

An ineffective radiator fan may lead to issues with your car’s AC because the radiator cooling fan generates twice as much air as the condenser fan. This fan draws air using a condenser, which extracts heat from the coolant flowing through the radiator. When the radiator cooling fan goes bad, it may negatively impact the AC’s efficiency.

Read More: Reasons Why Your AC Is Not Working

5) Blown Radiator Fan Fuse

The fan operates with the assistance of a fuse designed to shield it from electrical overloads. This fuse blows when there’s an amperage surge or a bad motor.

If your cooling fan is not working, you may try replacing the fuse and hope that the problem was just a temporary issue. But if the fuse keeps blowing, it signifies a more significant issue at hand.

6) Engine Overheating

The main function of the radiator fan is to cool down the radiator and engine. As the engine gets too hot, the fan starts working on its own. But when the fan motor goes bad, the fan can’t switch on, and the engine might get too hot and start to overheat.

Your vehicle dashboard has a temperature warning light or gauge that informs you if the engine is overheated. If you observe that your engine is overheating, you should turn off your vehicle right away. If you keep driving when the engine is too hot, it can damage the engine a lot, and fixing it could cost a lot of money.

The challenge with solely relying on this symptom to determine a faulty radiator fan is that several other issues can cause engine overheating. In some instances, the engine may overheat even when the fan is operating correctly. Hence, it’s crucial to accurately diagnose the problem before changing a component.

Causes of Bad Radiator Fan

Your radiator cooling fan goes bad due to one or more of the following causes:

Faulty Fan Motor: The cooling fan is driven by an electric motor. This motor helps the fan to work efficiently. When this motor goes bad, your fan won’t be turned on.
Corrosion: Corrosion may affect the working of the radiator fan with time, mainly if you drive your car in harsh conditions.
Faulty Fan Clutch: The mechanically driven fan contains a clutch. This clutch may wear out or fail over time, leading to the poor performance of the radiator fan.
Bad Thermostatic Switch: The thermostatic switch or thermostat acts as a sensor that regulates the operation of the radiator cooling fan based on the coolant temperature. A bad thermostat may not activate the fan when it is required.
Faulty Wiring or Fuses: Different electrical problems like blown fuses or damaged wiring may prevent your fan from getting power.
Damaged Fan Blades: If the blades of the fan blades are damaged or worn out, they can’t efficiently blow air through radiator fins. These blades may be damaged because of physical damage or wear over time.
Faulty Relay: A bad relay can prevent the fan from operating efficiently.

Radiator Fan Location

A mechanical radiator fan is typically positioned near the engine’s front, attached to the water pump pulley. But in the case of an electric cooling fan, you should find the plastic fan blades located directly behind the radiator. All modern vehicle models feature a cooling fan, though the designs of the two types may differ slightly.

Depending on your vehicle’s make, you might notice two fans on the radiator. This dual-fan design ensures that some cooling still happens even if one fan becomes non-functional.

How to Test a Radiator Fan?

Most new cars have an electric fan. One of the easiest ways to check if this fan is working is by using a tool called a multimeter. This tool can help figure out if there’s a broken fuse. Follow the below-given steps to test or check a radiator fan:

Begin by identifying the location of the fuse boxes in your car. This can vary depending on the make and model of the car. For this particular test, we will consider there to be an under-hood fuse box and an under-dash fuse box.
After locating the fuse boxes, set the multimeter according to the appropriate settings. Most vehicles are equipped with a 12V battery and are designed to handle this voltage. Adjust the multimeter to DC voltage. You can then choose the number range that will provide the most precise reading for a 12V circuit.
With the engine off, attach the negative wire of the multimeter to the negative battery terminal for under-dash fuses. Then, connect the positive wire of the multimeter to the fuse contact. Note that each fuse may have several contacts.
Assess the reading from the multimeter.
A reading around 12V signifies a properly functioning fuse. A reading of 0V on one contact and 12V on the other points to a blown fuse.
If you register 0V for both contacts, it suggests the fuse isn’t receiving power. This could mean it’s not correctly attached to the negative battery terminal or ground. If this happens, disconnect and retry the process.
If your tests determine you have a blown fuse, you will need to replace it to ensure the fan operates correctly.

Radiator Fan Replacement Cost

The replacement cost of a radiator fan depends on the vehicle model, labor cost, and brand type. The average replacement cost of the radiator cooling fan is from $480 to $800. In this cost, the labor costs from $160 to $260, while the parts cost from $320 to $540.

Frequently Asked Questions

What happens when a radiator fan stops working?

If your radiator malfunctions, it can lead to a noticeable whirring sound and a thermostat stuck in the open position, preventing the engine from achieving its usual operating temperature. A defective radiator cooling fan may also cause a circuit fuse to blow, a relay to malfunction, and the engine to overheat.

Can I drive with a bad radiator fan?

Technically, you can still drive your car if the radiator cooling fan fails. This is because the vehicle’s engine doesn’t necessarily require a cooling fan to function. But if the engine doesn’t get a consistent flow of air, your engine coolant will not cool down, and it may cause overheating. Therefore, it’s not recommended to drive long distances with a faulty radiator fan to prevent your engine from damage.

Does a cooling fan affect the AC?

The radiator fan has the responsibility to provide airflow over the AC condenser, ensuring the proper cooling of the coolant. This process allows your vehicle’s air conditioner to blow cooler air through the vents. If the fan isn’t working, the air conditioning might feel hot than usual.

How long can I drive with a broken radiator fan?

Driving with a malfunctioning radiator fan is not recommended. Without the fan, your vehicle’s radiator will be unable to get the necessary airflow to cool down the coolant. This can lead to rapid overheating of the engine. Driving an overheated car can cause severe damage and potentially leave you stuck, so it’s best to avoid this situation entirely.

How long does it take to replace a radiator fan?

A professional might need around one to four hours to change a radiator fan in most car models. However, if you decide to undertake the task yourself, it is recommended to allocate a bit more time since you may not possess the specialized tools and expertise that a professional mechanic would possess.

How often does a radiator fan need to be replaced?

A well-maintained radiator fan is expected to last between 8 to 11 years. To ensure this longevity, it’s important to keep the cooling fan clean from contaminants and also degrease it. Additionally, regularly flushing the coolant according to the owner’s manual guidelines is crucial to ensure the optimum performance of the cooling system.

Can AC work without a cooling fan?

As the air conditioner operates without a cooling fan, it could cause the evaporator coils to freeze. Once this occurs, your AC is vulnerable to more severe damage. In such a scenario, it’s best to switch off the AC and contact a professional technician.

Which mode of AC consumes less electricity?

By switching the AC to cut-off mode, it will use less power, which can contribute to lower electricity bills.

What are the signs of a bad cooling fan?

When a cooling fan goes bad, it produces different signs such as overheating, loud whirring noise, the fan not working, a blown fan fuse, or poor performance of the air conditioning system.

Written By

Engineer Rahela

Rahela is the owner and main author of Mechanicalspecial. She is an automotive expert writer. She have over four years of experience in the automotive writing niche and have completed over 700 pieces of content from 40 projects. She have good knowledge and skill in vehicle repairing, all mechanical work, car upgrades and maintenance.