How to Test a Radiator Fan with a Multimeter

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It can be quite a hassle testing a radiator fan using a multimeter if you are not experienced in handling electronics. However, this is still possible with a useful guide regardless of your level of experience or the brand of the radiator fan that you are looking to test. Typically, radiator fans are designed for various objectives, with the popular ones being the single-phase motors.

Moreover, there are also many others such as capacitors start motors as well as split-phase meant for industrial environments, and these are often used in warehouses plus factories. They perform the function of cooling the engine in the summer session and preventing the engine from freezing during winter. Therefore, if you are looking to learn how to test a radiator fan with a multimeter, read through this article, and you will gain some helpful insight on how to do this. 

Configure the radiator fan wires 

Radiator fans usually have two wires, which is a white and brown one, and both are typically plugged in the capacitor.

Make proper preparations before you start the tests 

Before you start running tests, make sure the power is off on both the radiator fan as well as on the main switch. It would be best if you also considered that the radiator fan might have broken down due to a damaged capacitor. Moreover, you must examine the capacitor before you commence testing since distorted capacitors and capacitors with dents or any form of the problem need an immediate replacement for everything to work correctly.

In case you detect a problem on your capacitor, it then means that your radiator fan does not have a problem. However, you should continue running a test on your radiator fans using a multimeter because if it has a problem, it could consequently trigger the capacitor to break down too.

How do you test a radiator using a multimeter? 

There are specific procedures you have to follow, and these are; 

Step 1 – Test the wires

To do this, you have to follow some steps below:

The value measured in the above procedures should either read one or two ohms. Therefore if everything, including the measuring value, is okay, place your white-brown wire on the side because it does not have any problem.

Step 2 – Test the second set of wires

To do this, start with the brown wire, and subsequently, the black wire, which is often considered to be the main wire. When you are running this test on the second set of wires, you also need to observe these steps, that is;

  • Place the negative multimeter probe, which is in black on the brown wire.
  • Put the red probe of your multimeter on your white wire.

If the readings displayed value is between 32-40 ohms, then your radiator fan is indicating a standard value; thus, it is not damaged. 

Step 3 – Next, test the third set of wires.

Follow the steps below:

  • Using the negative (black) multimeter, examine the lead that is still on the brown wire, pick a red test lead and remove it off of the white wire.
  • Finally, place the red probe on the popular wire

The value you get when measuring this phase of testing should be around 14 ohms. Therefore, in case it does not fall around there, consider your radiator fan to be slightly damaged, thereby meaning you need to either address the issue yourself or hire an expert who specializes in repairing electrical devices.

Step 4 – Finally, the fourth set of wires

You need to keep the red lead on the black wire and remove the black probe off from the white wire. Consequently, place the white wire place the probe, which is usually black, and your multimeter gives you a reading that is approximately 20 ohms.

Avoid moving the blade while running this particular test for safety reasons, as this might cause damage or an accident. However, if your blade is spinning as you run the test, your multimeter might give you an incorrect reading. Thus, you are hindered from getting an accurate value being displayed on the screen of your multimeter. 

When doing this, it is recommended you use south-wire clips as they do a superb job of preventing incorrect readings with this often an issue due to the different types of wires in your radiator fan.

Furthermore, you also need to know more about these wires, that is, how they function, with the black wire is frequently referred to as the common wire, whereas the brown wire is known as the start. The white wire, on the other hand, is called the run wire. In case your radiator wires differ from the configurations as mentioned above, please check for more details on your manufacturer manual script.

If you find it difficult locating the parts necessary for running the test, make sure you examine the metallic plate on the radiator fan. This plate usually contains all the details about the model of your radiator fans, such as the voltage and the manufacturer. Additionally, it also contains all the essential information that you will most likely need to help you run this kind of test while still observing the necessary precautions. 


Based on the above information, you can now successfully run a test on your radiator fan with a multimeter. This is because, thanks to the information as mentioned earlier, you are more knowledgeable about the radiator fan as well as how to use a multimeter to get the correct and accurate readings.

Although this at the start might seem to be challenging, the steps above will help guide you through your test and hence be able to identify the problem and consequently address it properly. Therefore, with a multimeter, your work is much simplified and easier.

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