A car’s radiator cooling fan is vital in keeping the engine temperatures down by reducing the temperature of the hot coolant as it passes through the radiator. It might surprise you to hear that radiator cooling fans fail regularly, so you are likely tempted into driving the car with it not working.
Before you read on, driving with the radiator fan not working is a terrible idea, and if it isn’t working, you should safely pull over and have the car recovered. Attempting to drive could have severe consequences if the engine was to overheat.
Can I Drive If the Radiator Fan Is Not Working?
In theory, it is possible to drive with the radiator fan not working, but it largely depends on the type of fan the driving you are doing. For example, if the vehicle is completely cold and you are just driving to the shops a mile down the road, it won’t be a problem; the car will probably not get hot enough to warrant the fan ever coming on. If there were heavy traffic, the vehicle would overheat at idle without the assistance of the fan to cool the engine. Also, If you have a mechanical engine-driven Fan, it may not be possible to start the car, let alone drive it.
If you are about to set off on a long journey or are in the middle of a long trip and the fan isn’t working, you should consider it unsafe to keep driving. Although, the air traveling through the radiator once you get up to highway speeds is more than a fan could produce to cool the engine. You will not know what slow-moving traffic or delays await you on the journey, at which point, any time you are driving under about 50kmph (30mph), the car will require the cooling Fan to work.
Either way, if you decide to keep driving, pay attention to the temperature gauge on the dashboard and immediately pull over. It starts creeping up to close the red. If the car does overheat, you can cause catastrophic engine damage.
How do radiator fans work?
Car radiator fans are an essential component that helps regulate the engine’s temperature. The fan works by pulling or pushing(depending on where the fan is mounted) air through the radiator core to cool the coolant, which is then pumped around the engine to reduce temperatures. The radiator fan helps to increase the airflow, thus the car’s ability to cool the coolant quicker and more efficiently.
There are two main types of radiator fans: mechanical and electric.
In a mechanical fan system, the fan drives by the serpentine belt connected to the engine’s crankshaft. As the engine RPM increases, so does the speed of the fan. The fans work by sucking more air through the radiator and into the engine bay. Although these fans work at all rates, they could be more efficient at cooling due to the distance between the fan and the radiator. This type of fan is typically found in older classic cars and trucks. To use old vehicles on modern roads, most drivers do away with mechanically driven fans and install or add supplementary, electronic cooling fans, which are much more efficient.
Electronic fans operate when a temperature sensor, usually mounted in the engine block, sends a signal to turn the fan (s) on and off. When the engine coolant reaches a specific temperature, the sensor signals the fan to turn on and start pulling/pushing air through the radiator. Once the temperature sensor cools down to a point, usually a couple of degrees below the fan switch on point, the fan then shuts off. Scientifically this is called hysteresis.
Some cars have two radiator fans, one primary and one secondary. The primary fan is the main fan that provides most of the cooling required for the engine. The secondary fan is usually only used when the AC is operating to draw air through the air con condenser radiator.
Signs the radiator fan is not working
Apart from the obvious the fan is not working, there are other signs you may think, hang on a minute; the fan hasn’t cut in yet and should have. They include:
- Battery charging light illuminated – On a mechanically driven fan, a battery charging light illuminating the dashboard could indicate the serpentine belt has snapped. Although the car will start to overheat when you begin to slow down, the battery will no longer be receiving a charge from the alternator, which the serpentine belt also operates, so the charging light might coming on might be the first indicator.
- Car overheating when stationary or driving slowly – The car overheating but only when traveling under 50kmph is a perfect indicator of a problem with the cooling fans’ operation. When traveling above these speeds, enough air passes through the radiator to keep the car coolant cool without a cooling fan working.
- Coolant warning light on – The coolant warning light can indicate either the coolant level is low or the coolant is overheating. Regardless of the problem, they can point to the radiator fan not working. If the coolant level is too low, there may be an air lock in the coolant system which means the sensor will not get the correct reading of the coolant temperatures.
- EML light on – The engine management light coming on can indicate a bad coolant temperature sensor, failed fan switch, or the thermostat is not operating; at this point, a sensor may not get hot enough, or the fan may not get a signal to turn on.
- Car has entered limp mode – The car entering limp will be for the same reasons as the EML light coming on. However, when the vehicle is in limp mode, it will be overheating, and the car is now protecting itself by restricting the revs and speeds the engine will drive. Although this isn’t usually a sign the fan isn’t operating, it may happen.
The risks of driving with the fan not working
As you may have guessed, the car will overheat if the cooling fan is not operating. When an engine overheats, it can cause a crazy amount of damage, and the whole motor, transmission, and all of the supporting components may need replacing, which will cost a fortune!
If you notice the fan not operating, do not continue or attempt to start driving. Even though this article says you can, it doesn’t mean you should. Moving the car a few yards will be fine if the motor is cold. But trying to drive from one town to the next is a bad idea that will probably end with the car breaking down.
How to fix a faulty radiator fan
- Check the Fan Fuse – The Fan may not work because of something as simple as a blown fuse. Check the fuse box to see if the fan fuse or others have blown. If so, replace it with a new one; most cars come with a few spares in the lid of the fuse box. Make sure to replace it with the correctly rated like-for-like fuse. Check the Fan Relay – The fan relay allows power to the fan. The fan may start pulsing or fail to operate if the relay is faulty. You can test the relay by swapping it with another one. If the fan starts working, then the relay is the issue.
- Check the Wiring – Inspect the wiring that connects the fan to the car’s electrical system. Look for any signs of damage, such as frayed wires or loose connections. If you find any issues, repair or replace the wiring as necessary.
- Install a fan override switch – Wiring the Fan to a flick on and off fan override switch in the cabin is relatively easy, but you need to understand the car’s electronics so you don’t cause a bigger problem.
- Replace the Fan – If the fan motor is faulty, you may need to replace it. This is a more involved repair; on some cars, they bolt in and out, and others require the whole radiator to be removed.
Although depending on how far and how fast you need to drive, it may be possible to drive for a short period with the radiator fan not working, but you should avoid doing so. Driving with the fan not working can result in the car overheating, which will be very costly to repair if the engine blows up!
It’s amusing how cars can go from one extreme to another! So, next, why not have a read of fan still running when the car is off? Here’s what’s normal! which is the complete opposite problem.