DIY Guide: How to Test Your Subaru Radiator Fan Like a Pro

Subaru cars are known for their durability and dependability. However, even the most reliable cars can experience issues from time to time. One common issue that Subaru owners may encounter is a malfunctioning radiator fan. A faulty radiator fan can cause the engine to overheat and lead to costly repairs. This article will guide you through how to test your Subaru radiator fan like a pro, including the tools needed, step-by-step instructions, and troubleshooting tips.

Understanding the Function of the Radiator Fan

The radiator fan is an essential component of your car’s cooling system. Its primary function is to pull air through the radiator to help dissipate the heat generated by the engine. The fan works by pulling cool air from outside the vehicle across the radiator, which then cools the engine coolant. If the fan is not functioning correctly, it can cause the engine to overheat, leading to potential damage.

Components of the Radiator Fan

Before we dive into how to test the radiator fan, let’s first take a look at its components. The primary components of the radiator fan are the motor, fan blades, and the fan shroud.

The motor is what powers the fan blades and is typically located in the center of the fan assembly. The blades are responsible for creating the airflow that cools the radiator. The fan shroud is a plastic cover that surrounds the fan and directs air through the radiator.

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Tools Needed to Test the Radiator Fan

To test the radiator fan in your Subaru car, you will need a few tools, including:

  • A voltmeter
  • A set of pliers
  • A flathead screwdriver
  • A paperclip (optional)

Step-by-Step Instructions to Test the Radiator Fan

Follow these step-by-step instructions to test your Subaru radiator fan:

  1. Turn off the engine and let it cool down completely.

  2. Locate the radiator fan switch. Depending on the model of your Subaru car, this switch can be found either on the radiator or on the thermostat housing.

  3. Disconnect the electrical connector from the fan switch.

  4. Turn on the ignition to the "on" position.

  5. Using the voltmeter, check for voltage at the electrical connector. There should be approximately 12 volts of power at the connector. If there is no voltage, check the fuse and relays related to the radiator fan.

  6. If there is voltage, use a paperclip to jump the electrical connector. Insert one end of the paperclip into one of the holes on the connector, and the other end into the other hole. This will bypass the switch and activate the fan.

  7. Observe the fan blades for movement. If the blades do not move or move slowly, the motor may be faulty.

  8. If the blades move correctly, test the fan shroud by using the flathead screwdriver to block airflow through the radiator. If the fan speed increases, the fan shroud is functioning correctly. If the fan speed does not increase or only slightly increases, the fan shroud may be faulty.

  9. Reconnect the electrical connector to the switch and turn off the ignition.

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Troubleshooting Tips

If you encounter any issues while testing your radiator fan, there are a few troubleshooting tips you can try before seeking professional help.

One common issue is a blown fuse or faulty relay. Check the fuses and relays related to your radiator fan and replace any that are damaged.

If the fan motor is faulty, it will need to be replaced. Similarly, if the fan shroud is faulty, it will need to be repaired or replaced.


Testing your Subaru radiator fan is an essential part of car maintenance that can save you money on costly repairs in the long run. By following the step-by-step instructions provided in this article and using the tools required, you can test your radiator fan like a pro and troubleshoot any issues that may arise. Remember to take safety precautions and let the engine cool down before testing the fan. Happy testing!


Q: What does a faulty radiator fan sound like?

A: In some cases, a faulty radiator fan may make a grinding or rattling noise.

Q: Can I test my radiator fan without a voltmeter?

A: While a voltmeter is not necessary, it is recommended to ensure accurate results. If you do not have a voltmeter, you may be able to test the fan by simply turning on the engine and observing the fan blades for movement.

Q: How often should I test my radiator fan?

A: It is recommended to test your radiator fan once a year or if you suspect any issues with your car’s cooling system.

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Davis Bellew

As a Subaru owner and enthusiast, Davis has a deep understanding of the needs and concerns of Subaru drivers. He specializes in writing informative and engaging content about Subaru maintenance and repair, and his articles are always well-researched and easy to understand. When he's not writing, he enjoys hiking and photography.

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