Bad Radiator Fan Symptoms, Causes, and How to Check It

The radiator fan is one of the major parts of the engine cooling system. The radiator fan is also known as a cooling fan. All the latest vehicles have a cooling fan to extract heat from the coolant circulating throughout the engine. It helps to protect the engine from overheating. As the radiator fan goes bad, it generates different signs through that you can identify and fix the fan. This article explains the bad radiator cooling fan causes, symptoms, and how to test it.

What is a Radiator Fan?

The radiator fan is a cooling system fan that blows cold air through the radiator to lower the temperature of the coolant and cool the car engine. The radiator fan is located between the engine and the radiator. It is especially helpful when the vehicle is stationary or running very slowly to pump air to the grill.

Radiator Fan, cooling fan

The main function of the cooling fan is to extract the coolant heat and prevents the engine from overheating. Therefore, the efficient working of the fan is very important to prevent the engine from overheating and other damage.

This fan blows air via the radiator to lower the engine temperature. It is often employed at low speeds and will idle when air cannot flow naturally by the system.

If the air that cools the radiator does not flow through the radiator, the engine will start to overheat.

Engine overheating is one of the most common symptoms of a bad cooling fan. Also, the air conditioning performance may be poor than usual, or you may hear a growling noise coming from the engine compartment.

Symptoms of a bad Radiator Fan

If you notice any sign of a faulty radiator fan, you must replace or repair it as soon as possible. As the radiator cooling fan goes bad, it produces one of the below-given symptoms:

  • Engine Overheating
  • Air Conditioner Not Working
  • Temperature Warning Light
  • Hot Coolant
  • Loud Noise Coming from Cooling Fan
  • Fan Doesn’t Activate

1) Engine Overheating

Engine overheating is one of the first symptoms of a bad radiator cooling fan. The main function of the cooling fan is to properly cool the hot coolant and prevents the engine from overheating. As the fan fails, the coolant will be unable to properly extract the engine due to the engine will overheat.

engine overheating

The engine overheating may generate the following issues:

  1. First, the engine may badly damage, which leads to more repair work.
  2. Second, the vehicle may not be able to drive until you fix the problem.

Read More: Overheating Symptoms and Causes

2) Air Conditioner Not Working

It’s often overlooked, but a radiator fan plays a crucial role in a car’s air conditioning system. The radiator fan, in particular, is tasked with drawing air over the AC condenser.

Car Air Conditioner

So, if your air conditioning isn’t cooling as it should, or the air feels warm, the fault might lie with a malfunctioning cooling fan. This could be more evident when you’re driving at slower speeds, where there’s less natural airflow over the condenser.

However, this symptom alone doesn’t necessarily point to a faulty radiator fan. More commonly, issues with air conditioning arise from problems with its specific components. Nevertheless, if you notice this, along with other signs we’ve discussed, it would be wise to inspect the cooling fans.

3) Temperature Warning Light

The temperature warning light shows a problem with the cooling system. This light is located on the vehicle dashboard. This light shows a warning because of the high engine temperature.

Temperature Warning Light, symptoms of bad radiator fan

In such a condition, turn off the engine and waits for cooling. After engine cooling, inspect the vehicle and find the reason for the engine’s high temperature. The temperature warning light may appear because the cooling fan is defective or underperforming.

4) Hot Coolant

Hot Coolant

The coolant is a liquid used to extract the engine temperature. It ensures the proper cooling of the engine. As the coolant extracts the engine heat, it becomes hot and sent into the radiator, where the radiator fan cools the coolant. If the fan is failed, the coolant doesn’t cool and causes engine overheating.

5) Loud Noise Coming from Cooling Fan

Strange Noises from cooling fan

If any part of the radiator fan is damaged, you may hear loud noises. You must understand how your car performs, including the unusual noises coming from the engine compartment. In such a case, immediately contact a mechanic to fix the problem.

6) Fan Doesn’t Activate

radiator fan motor

When the radiator fan stops working, it means that it has gone bad. In such conditions, the fan motor may burn out or malfunction.

In any way, if the fan is not working, you should understand that there is a problem with the fan. If this continues, it may lead to bigger problems.

Read More: Bad Cooling System Symptoms and Causes

Cause of A Radiator Fan

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

  • Blown Radiator Fan Fuse
  • Faulty Fan Relay
  • Insufficient Coolant
  • Physical Damage
  • Bad Coolant Temperature Sensor
  • Broken Wiring
1) Blown Radiator Fan Fuse

Maximum parts of electric vehicles use circuit fuses. Similarly, the cooling fan also has a fuse. As the fuse blows, the fan motor stops working. In case of a blown or burned fuse, the fan couldn’t receive power from the system.

Radiator Fan Fuse

The fan motor failure or power surge can also blow the fuse and prevent damage to other components. In case of a blown fuse, you must replace it immediately for the efficient working of the fan.

2) Faulty Fan Relay

The radiator fan often requires a significant amount of current, and thus, there’s a relay that supplies power to it. This relay can be damaged, preventing the radiator fan from operating.

The fan relay is typically positioned in the engine compartment’s fuse box. However, it’s always a good idea to refer to your manufacturer’s manual to determine its exact location.

3) Insufficient Coolant

If your vehicle has insufficient coolant, it could potentially push air into the cooling system, leading the coolant temperature sensor to misread the actual coolant temperature. In such a situation, it’s crucial to refill the coolant tank.

Coolant level, causes of bad cooling fan

A low coolant level may lead to engine overheating and, in a worst-case scenario, may also cause the engine to seize. Overheating due to coolant loss can badly damage your engine, resulting in significant repair costs. Therefore, you should always maintain sufficient coolant levels in your vehicle.

Read More: Coolant Leak Symptoms and Causes

4) Physical Damage

If your radiator fan isn’t functioning, it could indeed be attributed to defective radiator fans. Your fan may be damaged by an accident or harsh conditions. The electric motors within these fans can degrade over time and eventually fail.

To test the electric radiator fan quickly and easily, you can follow these steps:

  • Get a wire from the car battery.
  • Disconnect the fan connector.
  • Then, put a protected 12v+ wire (a wire with a fuse) and a ground wire into the connector.
5) Bad Coolant Temperature Sensor

Car models generally use one of two systems: either the fan control is integrated with the motor control unit, or there’s a separate fan control module. In both scenarios, these control mechanisms rely on a temperature sensor to determine when to engage the cooling fans.

Coolant Temperature Sensor

Your vehicle’s radiator fan won’t operate efficiently when the coolant temperature sensor goes bad. Few vehicles have distinct engine coolant temperature sensors for the engine control module (ECM) and the radiator fan.

6) Broken Wiring

If your engine is overheating and the radiator fan isn’t activating, the issue may stem from faulty wiring or a poor connection. Inspect the wires that connect the relay or controller to the radiator fan. Look for any signs of corrosion on the connectors.

Testing wires with a multimeter isn’t always the best way to check if they’re working because you really need to put them under stress to know for sure. But you may use a multimeter as a first step to see if electricity is getting to the radiator fan.

Read More: Reasons Why Your Car Loss Power While Driving

Function of Radiator Fan

The main functions of the radiator fan are given below

  1. The main function of the cooling fan is to remove excess heat from the engine and coolant. When the coolant extracts the engine heat, it goes into the radiator, where a fan blows cold air and removes the coolant heat.
  2. It can work efficiently when the engine is off, and air cannot flow through the grille.
  3. Cooling fan assists in attaining atmospheric airflow when it’s moving too slowly.
  4. The electric cooling fan regulates the car temperature by turning it on and off according to the engine temperature.

How to Test a Radiator Fan

Follow the below-given steps to test a radiator fan:

Step 1: Check the Radiator Fan Type

Check if the radiator fan is manual or electric. The manual radiator fan is bolted to the water pump and runs on the same belt as the water pump. The electric radiator has wires that connect to the car’s electrical system.

To check the electric radiator fan, start the car and bring it up to a temperature where the fan starts up normally.

Step 2: Connect Voltmeter

Use a voltmeter to test the cable’s performance. Connect one end of the voltmeter to the ground and the other end to the electrical connector on the fan. The voltmeter gives you a voltage reading.

The normal voltage for a cooling fan is about 12 volts. If the voltmeter shows 12 volts, the problem is not with the power supply, but the fan needs to be replaced.

If the voltmeter shows no current, check the fuse.

Step 3: Check the Fan Belts and Screws

For manual radiator fans, do a visual inspection first. Make sure the four screws holding the radiator fan are tight. Make sure the belt is in good condition and under tension.

Step 4: Check the Fan Clutch

Some manual radiator fans come with a fan clutch. There is a spring in the fan clutch to speed up the rotation of the fan. If the radiator fan has a fan clutch, check the radiator fan with the engine running. The cooling fan must run faster than the engine speed. If not, the fan clutch is defective and needs to be replaced.

Some radiator fans have a fixed mount and no fan clutch. If the radiator fan is permanently installed and not working, the belt has snapped and needs to be replaced.

FAQ Section

What is the function of a radiator fan?

The main function of the radiator fan is to cool the hot coolant of the radiator by blowing cold air. It is located in between the car engine and radiator.

What are the types of radiator fans?

  • Mechanical radiator fan: It is directly connected to the engine water pump pulley. It is driven by a belt. A crankshaft is connected that takes power from the engine. 
  • Electric radiator cooling fan: It is driven by an electric motor. It locates directly to the radiator for efficient cooling.

What causes the radiator fan to go bad?

  1. Vehicles that daily travel long-distance or stop frequently are prone to failure of the radiator fan assembly.
  2. Age of the cooling fan
  3. Blown fuse 
  4. Bad connection or broken wiring 
  5. Damaged or bad coolant temperature sensor
  6. Insufficient coolant
  7. The bad fan controller module
  8. Engine overheating
  9. Damaged fan relay 

How do you know if your radiator fan is bad?

When your radiator fan doesn’t work, your car is at risk of overheating, particularly when idling or moving at slower speeds. While at higher speeds, the wind can provide some cooling effect, it’s not sufficient to entirely compensate for a non-working fan. Nevertheless, it is crucial to address an overheated engine promptly as it can lead to significant damage, making it important to avoid taking any risks.

Can I drive without a radiator fan?

Yes, you can drive the vehicle without a radiator fan, but you shouldn’t drive. The main function of the radiator fan is to properly cool the coolant and prevent the engine from overheating. But if your car doesn’t have a radiator fan, your engine will ultimately overheat, which may cause an expensive repair.

Can a bad thermostat cause the radiator fan not to work?

The thermostat works as a valve that allows coolant to flow in and out of the radiator. If it doesn’t open when the engine temperature becomes higher than normal, the coolant will get stuck into the block, which may cause engine overheating. This will stop the working of the radiator fan.

What sensor controls the radiator fan?

The operation of the radiator fan is controlled by the coolant temperature sensor (CTS). While certain cars may have a dedicated CTS for the radiator fan, but in most vehicle models, it is controlled by the same coolant temperature sensor utilized by the engine control module (ECM).

What are the symptoms of a bad cooling fan?

  • Fan doesn’t activate
  • Engine overheating
  • A/C system not working
  • Temperature warning light illumination
  • Hot coolant
  • Loud noise coming from the cooling fan
  • Unexpected shutdowns

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