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How to Check if a Radiator Fan Is Working (Step-by-Step)

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Last Updated on: 7th September 2023, 12:36 am

Without a working radiator fan, the engine can quickly overheat, leading to serious damage. This is why it’s important to check if the radiator fan is working correctly.

One way to check the radiator fan works is by turning on the AC or listening for it while the coolant temperature is elevated. You can also perform a continuity test using a digital multimeter.

In this article, we’ll discuss how to check if the radiator fan works, why its important and the various methods to do.

radiator fan and shroud

What Tells the Radiator Fan to Turn On?

The ECU determines when the radiator fan switches on and off.

If the coolant temperature surpasses the desired temperature range, the engine’s computer activates the fan relay.

The relay then switches on the cooling fan, helping to circulate airflow through the radiator, cooling down the coolant fluid.

Types of Cooling Fans

There are usually two types: mechanical and electronically controlled fans.

  • Mechanical fan: Operated through a belt linked to the engine, the mechanical fan’s activation is managed by a clutch mechanism. These are common in older vehicles but have become less common in modern ones.
  • Electronically controlled fan: Propelled by an electric motor and governed by the engine’s computer, electronically controlled fans are very common in modern vehicles. These fans are renowned for their efficiency and low noise levels.

Way to Check if the Radiator Fan Is Working

Below are two easy methods to check if the radiator fan is working or not.

1. Check by listening for the fan to turn on

When the engine coolant reaches an elevated operating temperature (above 190 to 225 degrees Fahrenheit / 75 to 105 degrees Celsius), the fan should activate.

If the coolant temperature is elevated you should begin to hear the radiator fan spinning.

However, the fan will only start up if the coolant surpasses the temperature range, which usually only happens during high-temperature weather, sitting in traffic congestion, or hard driving.

2. Turn on the AC

Certain vehicles have a default mode where the radiator fan activates automatically when switching on the AC.

However, this may not be the case with all vehicles and it shouldn’t be a determining test.

How to Check the Fan Fuse

Follow the steps below to check the radiator fan fuse. To conduct a continuity test, you’ll need a digital multimeter.

  1. Firstly, identify the fuse boxes, which might be situated beneath the dashboard or under the hood.
  2. Once located, set your multimeter to operate in Direct Current Voltage (DCV) mode. This setting aligns with the typical 12V battery voltage used in most cars.
  3. Power down the engine and connect the black lead (representing negative) to the negative battery terminal. This step pertains to the under-dash fuses. Attach the red lead (representing positive) to a contact point on a fuse. Multiple contacts will be present on each fuse.

Observe the reading displayed on the multimeter.

  • If it hovers around 12V, the fuse is performing as expected.
  • Encountering 12V on one contact and 0V on the other indicates a blown fuse.
  • If both contacts show 0V, it signifies that the fuse lacks power connection.

This scenario might stem from an improper link to the negative battery terminal or the ground.

How to Test a Radiator Fan Motor

To test the radiator fan motor, you can do a continuity test.

  1. Use a multimeter adjusted to the continuity setting.
  2. With the engine turned off, disengage the electrical connector linked to the fan motor.
  3. Place one probe of the multimeter on one terminal of the connector and the other probe on the opposite terminal.

A beeping sound from the multimeter confirms the motor’s continuity. Whereas the absence of a beep indicates an issue with the motor.

mechanic holding a car fuse


To check the radiator fan, you can test the fuse and conduct a continuity test on the fan motor.

Several issues point to a malfunctioning radiator fan, including unusual noises, overheating, the smell of burning, blown fuses, etc.

  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer. He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

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