How to check a radiator fan

Has your car been overheating? Maybe it’s time to assess your radiator fan

Has your car had insufficient cooling recently? A car’s cooling system makes use of a radiator and fan to ensure the engine doesn’t overheat while driving.

If the fan isn’t operating properly, it can lead to overheating fast and stop you in your tracks. Prolonged overheating can also damage engine parts, so it’s important to get the problem checked out as quickly as possible.

Suspect the radiator fan has failed? Then this guide is for you. We’ll take you through step-by-step instructions on how to check your radiator fan and what to do if it has stopped working.

Natrad has a range of radiator fans for a huge variety of vehicles. Need to replace your radiator fan, or other parts of your cooling system? Talk to one of our specialists.

How to check a radiator fan

Most cars have a fan near the radiator that aids airflow to help cool the coolant fluid flowing through its tubes. This process is essential to keep the engine at optimum temperature and the system working properly.

If your radiator’s cooling fan stops working, your engine could start to overheat and might even break down.

Not to worry — we’ll take you through step-by-step instructions on how to check your radiator fan and what to do if it has stopped working.

Natrad stocks a wide selection of high-performance mechanical and electric radiator fans suitable for all vehicle makes and models. Nip into your nearest Natrad store, and we’ll give your car’s cooling system a full assessment.

1. Check if your car’s overheating

An overheating engine on the verge of a breakdown can be a big problem. The good news is that it’ll likely never come as a surprise. It’s actually quite easy to tell when your car is beginning to overheat. Here are some of the most common symptoms:

  • Your check engine light may turn on
  • There may be steam coming from the hood
  • If your car has a temperature gauge, then this will also indicate an increase in temperature

Now you know there’s a problem, the next step is fixing it. We’re going to assume that your radiator, water pump and coolant have already been checked and found to be in good order. The next step is checking your radiator fan.

2. Identify what type of radiator fan you have

CAUTION: Fans can rotate at high speeds and can be dangerous. Never allow tools, any part of your body or clothing near a moving fan.

There are two main types of radiator fans: mechanical and electrical. They operate in different ways, and their reasons for breaking down vary, so knowing the kind of fan your car has will help you diagnose the problem. 

A lot of older cars will have a mechanical fan clutch, which is driven by a belt and pulley system. This means it is powered directly by the engine. 

Modern cars tend to have electrical fans which are powered by the vehicle’s electrical system. This allows them to be more efficient (sensitive to temperature and only operating as extra cooling is needed). 

Signs and symptoms of radiator fan failure

Ways to tell if your radiator fan is to blame for overheating include the following:

Mechanical radiator fan failure

  • Damaged or missing fan blades
  • Fan drive belt failure
  • Seized fan (unable to be rotated)

Most obvious causes can be detected visually or tested physically.

If you don’t feel confident in tackling this yourself, contact a cooling specialist at a Natrad store near you.

Electrical radiator fan failure

  • Damaged or missing fan blades
  • Broken wiring or bad connection
  • Blown fuse
  • Faulty fan relay
  • Motor failure
  • Failed controller module
  • Defective coolant temperature switch

If you’re unsure whether you might have any of these problems, leave it to our Natrad technicians.

3. How to check your radiator fan

checking a radiator fan

As most modern cars have an electric fan, we’ll go through one of the easiest ways to test this kind of fan – by using a multimeter.

A multimeter is a handheld device used to test the strength of electrical currents. You can pick one up at most trade stores.

Here are step-by-step instructions on how to use a multimeter to test radiator fan voltages.

  1. Firstly, you’ll need to locate the fuse boxes on your vehicle. This may differ from car to car, so for the sake of this test, we’ll assume there is an under-dash fuse box and an under-hood fuse box.
  2. Once they are located, you will need to set your multimeter to the correct setting. As most cars have a 12V battery (with negative to earth) and are calibrated to take this much voltage, set your multimeter to Direct Current Voltage (DCV). You’ll also be able to select which number range will be most accurate for a 12V circuit.
  3. From here, make sure the engine is off with accessories powered on, and connect the black lead (negative) to an earth point. This is for under-dash fuses. Next, connect the red lead (positive) to the fuse contact. There will be multiple contacts on each fuse.
  4. Evaluate the reading. If the reading is about 12V, then the fuse is working correctly. If you get 12V on one contact and 0V on the other, then this indicates a blown fuse. If you get 0V on both contacts, there is no power connected to the fuse. That likely means it is not properly connected to the negative battery terminal or ground. Detach and try again.
  5. If you have determined that the problem is a blown fuse, this will need to be replaced to ensure the fan works as it should.

If your fuse doesn’t seem to be the issue, nip into your nearest Natrad store. Our qualified specialists can determine the cause of the failure and recommend the best course of action.

Is it safe to drive a car with a broken radiator fan?

The radiator fan assists in directing air through the radiator when the ambient air flow is not sufficient. While the vehicle is in motion and air is moving through the radiator, a broken car radiator fan will have little impact. When stationary or spending time in heavy traffic without a working fan, your engine may overheat, which could cause irreparable and expensive damage.

If your nearest Natrad store is only a few minutes away, then you might decide to drive your car in rather than call a tow truck. It is possible to make the trip, but you need to be careful to avoid overheating your engine. 

While driving, keep a close eye on the engine temperature gauge or watch for a warning light. If the engine gets too hot, pull over and turn the engine off so it can cool down before you resume your drive.

Repair or replace your radiator fan

If the issue is with the fan itself, most likely it will need replacing. Electric fans in particular need to be replaced as the internal fan motor cannot be repaired (if the motor is the cause of failure). Fans are not a very costly part and, as they are easy to access, the labour involved is not expensive either. Mechanical fans are generally quite an easy fix too.

Nip into your nearest Natrad store for specialist advice on radiator fans. Our friendly team can test, diagnose and recommend the best fan replacement or repair options for your vehicle.