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How to Test Radiator Fan with Multimeter

The main function of a radiator fan is to prevent the engine from overheating. It distributes cooler air through the radiator and exchanges the engine heat. This fan, having four to eight blades, rotates quickly to send cooler air to the engine. It works as a part of the overall cooling system. If the fan shows any problem or stops working, you can use a multimeter to check if it has the correct voltage and its motors are working. Do you know how to test radiator fan with multimeter?

There is a sensor on the bottom passenger side of the radiator. It does the job of taking notes of coolant temperature. It sends signals to the radiator fan to turn on when the temperature crosses 172°F. The fan should also turn on after switching on the air conditioner. There must be a problem with the fan if it does not spin when it should and spins when it should not. In either case, you can detect the issues by using a multimeter.

multimeter testing
Find out the problem with a multimeter.

How to Test Radiator Fan with Multimeter

If the radiator fan is not running, you have to check its fuses to find out if the problem is with the fan itself or other components in the system.

Here’s how to test radiator fan with multimeter by checking the fuses.

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Examining the Fuses with a Multimeter

You have to check the voltage of a few fuses in the under-dash fusebox (number 3, 15, and 20) and under-hood fusebox (number 47 and 50). Kick off the engine or switch the ignition key off to IG2. Set the multimeter’s meter to ‘20’ in the DCV section as you will be testing 12V circuits.

The black multimeter probe will go to the negative battery terminal (for under-hood fuses) or a metal ground point on the car (for under-dash fuses). Each fuse has two contacts where you have to touch the multimeter’s test probes to get the readings.

how to test radiator fan with multimeter
Check the fuses one by one.

Touch the red probe to any of the two contacts and take the reading. The value should be around 12 volts. No need to worry about recording the precise voltage reading because it varies due to several factors including the alternator output and the charge in the battery. Touch the robe to another contact and take the reading.

Now, what do the readings mean?

12V on both contacts. It means the fuse is working fine and you can just move on to check the next one.

12V one contact and 0V on the other. This is the sign of a blown fuse. You need to replace it.

0V on both contacts. It means the fuse does not have any power, which is only possible if the black probe is not properly connected to the negative terminal of the battery or the grounded to a metal part. Detach the probe and then reconnect again to take readings.