Check if the fan is working. Automatic fan speed control to reduce noise

The combustion of fuel in the ICE cylinders is accompanied by the release of a significant amount of heat, only a part of which is used by the engine and converted into mechanical energy. The rest is uselessly lost, and special devices have to be used to neutralize its excess. These include cooling system, the ability to work in any conditions provides a cooling radiator fan.

The principle of operation of the radiator fan

Before considering this issue, let's touch on the whole, what is the water cooling system of the internal combustion engine, shown below in the figure. It will allow us to remember the principle of its work.

In cases where a cold liquid passes through the motor jacket, it takes away excess heat, while the engine cools and the water heats up. Then it passes through the radiator, where it gives off the received heat to the atmosphere, and again enters the engine.

The design of the radiator is a set of thin tubes that create a large cooling surface. The oncoming air flow, passing through it, carries away the excess heat that is stored in the liquid. In cases where there is no oncoming air flow (engine idling, traffic jams and other similar situations), or it is not enough to cool the water to the desired temperature, the operation of the cooling radiator fan is provided.

To do this, there is a special control circuit, the basis of which is the thermal switch of the radiator fan. It controls the temperature of the liquid. When it exceeds the set limits, the sensor is triggered, at its signal the radiator fan turns on, which creates the necessary air flow. This flow cools the heated water, and when its temperature reaches the required value, the sensor again triggers and turns off the airflow.

This is how you can describe the basic principle by which the radiator fan works - it turns on when the water temperature exceeds the set one, and turns off after it drops to the desired value.

What is fraught with if the radiator fan does not work

An internal combustion engine is a complex device, and its performance is optimal when it operates at a certain temperature. As noted above, it depends on the correct operation of the cooling system. In the case when it is not possible to withstand the desired temperature, the consequences will be rather sad - if the engine overheats, it may well jam and then, at least, it will be overhauled.

The stability of the entire system should create a fan, allowing you to reduce the temperature of the water in any conditions. But if it does not work, especially when it is hot, then you need to look for why the fan does not turn on or does not spin. Now such devices are usually electrical, and the failure of the product itself is unlikely, and a possible reason for this is often the failure of its strapping (sensor, fuse, connecting wires, etc.).

This means that when figuring out the reasons why the radiator cooling fan is constantly running or why it does not turn on or does not spin, it is necessary first of all to check the device piping.

How to check the radiator fan

As we have already established, the radiator fan should turn on when the water (antifreeze) temperature exceeds the set value. You can check this by reading the instruments on the front panel. If the fan does not turn on, then you need to check the entire signal chain.

1. Check the presence of the supply voltage coming to the product. To do this, you can use a tester or a light bulb. Lack of voltage will indicate a possible blown fuse or poor contact in the wires.
2. The health of the fan itself can be checked by applying voltage to it directly from the battery. If it spins, then everything is in order with it, and the defect must be sought in other devices. If not, and the fan does not spin, then the cause of the defect is in it. In principle, in this case, you can not stand still and move on, but you must constantly monitor the temperature of the engine. When the arrow approaches the red sector, you need to stop, open the hood and cool the engine. Two tricks will allow you to move in this case too. Keep a speed of at least sixty km / h, then a constant oncoming flow of oncoming air will cool the water passing through the radiator, and you will be able to move normally as long as you maintain speed. Another technique that allows you to partially replace a non-working fan is to use heating. Switch the stove to the maximum heating mode, in this case, part of the excess heat will go through the heater. True, in the cabin it will be like in a bath, but you can get to the nearest service station.
3. To check the sensor, it is necessary to disconnect the wires from it and close them together. If at the same time the fan turns on and spins, then the sensor itself does not work, it cannot be repaired, only replaced. However, if you leave the wires closed, then you can move on, with this option the fan spins constantly, although it is possible that the engine temperature will be lowered, but this is better than standing still.

Radiator fan runs continuously

Partially, such a case is discussed above, the reason is the failure of the temperature sensor or the short circuit of the wires going to the fan. But if it is constantly spinning, then this may be caused by the sticking of the relay. This happens quite often, especially after the relay is triggered and the fan should turn on.
Sticking relay contacts means that they cannot open, which causes a constant supply of voltage to the contacts, as a result of which the electric motor is constantly spinning. The consequences of sticking relay contacts include the fact that the radiator fan does not turn off.

Often the thermostat can be the reason that the fan shutdown does not work.. The fact is that the sensor is located in the head of the block, it is he who determines when the fan should turn on. But the coolant can move in a large and small circle, when it moves in a small one, it does not enter the radiator for cooling. The water movement mode is determined by the thermostat.

If it is stuck in the position of water movement in a small circle, then it will continue to move, overheat, which will trigger the sensor and turn on the fan, but because water does not enter the radiator, it will not cool, and the sensor will constantly signal a high temperature. As a result, the radiator fan does not turn off. Such a case is determined simply - you need to touch the hoses going to the radiator. When the thermostat is stuck, they will be cold when the engine is overheated.

If the radiator fan does not turn off due to a stuck thermostat, then sometimes you can knock on the case to eliminate this phenomenon. Often this is enough, and the defect disappears. If everything remains unchanged, then you will have to remove the thermostat, remove all the stuffing from it and then put the device itself in place.
Another variant of the same defect would be the thermostat jamming in an intermediate position. It can also cause the radiator fan not to turn off, but this situation is much more difficult to diagnose. Such difficulties are caused by the fact that a certain amount of water enters the radiator, but it passes too little, all the water does not have time to cool, which leads to engine overheating.

All of the above is not a complete description of the possible reasons why the radiator fan does not turn off. There can be many of them, sometimes quite strange and unexpected, but in each of these manifestations of malfunctions, it is necessary to look for causes and conduct a thorough analysis.

Radiator fan turns on early

The other extreme is when the fan turns on early. In this case, you need to look again at the temperature sensor. It most likely needs to be replaced. Unless, of course, there is a correct sensor. The fact is that sensors are designed for different temperatures, they are also called summer and winter, each of them must be switched on in its own temperature range. The latter work later. And if you have been using these all the time, then it may seem to you that the fan turns on early, although it happens on time and everything works correctly.

You have to really appreciate how early everything happens. If early switching is set according to indications on the instrument cluster, then this is not an indicator. However, when such an inclusion causes concern, connect the appropriate equipment through the diagnostic channel and see the actual sensor thresholds.

Cooling the engine of the car is the most important task. If the engine is allowed to overheat, then at best it will need to be overhauled. The ability to operate the car in any conditions is ensured by the reliable operation of the cooling system, which is largely determined by the correct operation of all its components.

You can check the laptop cooler for performance using the SpeedFan program or by connecting to another computer. Fan problems detected should be corrected as soon as possible to avoid overheating of components.

Program check

You can make sure that the fan is working without using special software. It is enough to bring your hand to the opening of the cooling system on the case, having loaded the system before that. Try, for example, running a resource-intensive game - the noise from the cooler will tell you that the laptop is trying to cool the components.

If the fan fails to keep up with the load and the component overheats, the laptop may freeze or shut down on its own. This is how the overheating prevention system works, but if it had to come into play, it means that the cooler is really bad, and it needs to be cleaned or replaced urgently. But this way you can only determine the fact of the operation of the fan. Whether it functions well can be found through the SpeedFan program.

It is not necessary to change the language: SpeedFan will clearly demonstrate with the help of icons which components are heated within the normal range and which are too hot. For example, in the example above, the cooler cannot cope with the cooling of the processor, so there is a fire icon next to the CPU.

Try to fix this with SpeedFan by increasing the fan speed of the laptop. Find the cooler at the bottom of the main window of the utility, which is responsible for cooling the CPU. If it's not running at 100%, increase its power to see if the CPU temperature drops. If even at maximum speed the fan cannot provide normal cooling of the laptop component, then it is necessary to determine what is the reason for the laptop overheating.

Hardware check

If it is difficult to understand if the fan is working, you will have to disassemble the laptop and check its operation. Before removing the cooler, read the disassembly instructions for your laptop model. If the laptop is still under warranty, then you should not disassemble it. Go to a service center with an overheating problem so as not to void the warranty due to mechanical interference.

If you are still going to disassemble the laptop yourself, then remember that it is not necessary to pull the cooler out of the case, it is enough to free the wires so that you can test the fan on another device. To check, you will need a USB cable, which has a plug on one side and two wires, red (+) and black (-) on the other. It is necessary to connect the wires of the USB cable with the wires of the cooler - black to black, red to red. The USB is then inserted into another computer.

If the laptop fan is spinning, then the cause of the temperature rise must be looked for elsewhere. Try replacing the thermal paste on the processor, clean the cooling system well again.

Cooler cleaning or replacement

If you get to the laptop cooler, you can try to clean it from dust or replace it yourself. Radiators with fans should be looked for in the hottest spots - near the video card, processor, hard drive. The cooler itself will be fixed with screws.

You can clean the fan with a regular cloth or a special brush. Then it is necessary to remove the radiators and also remove the accumulated dust from them. In principle, this completes the cleaning of the cooler, it remains only to install the cooling system in place without confusing anything. If you do not have experience in carrying out such operations, then it is better to immediately trust the professionals and contact the service center.

This cleaning is recommended to be carried out regularly, even if you do not notice problems with overheating of the equipment. Close attention to the condition of the cooling system should also be paid if there are animals in the house or if repairs have recently been carried out with "dusty" work - for example, rubbing of plastered walls. If the laptop components are still not cooling properly after cleaning the cooler, replace the fan with a more powerful one or consider purchasing a cooling pad.

I welcome you friends to the DIY car repair site. The radiator cooling fan is a device that allows you to forcefully blow the surface of the cooling device and reduce the temperature of the antifreeze (water) to a safe value.

Most often, the fan starts automatically when driving for a long time at low speed or while the car is parked with the power unit running.

As already mentioned, the fan has one task - to dissipate heat as much as possible around and thus protect the engine from overheating. The device is started automatically after reaching the maximum permissible engine temperature.

In modern VAZ cars, the temperature sensor sends a signal to the computer, which in turn gives a command to the fan (but more on that below).

The main types of radiator cooling fans

Today there are only two types of fans:

• Mechanical;
• electronic.

Mechanical (works when the crankshaft rotates). To maintain the integrity of the device and the blades at high speeds, the fan impeller is connected to the pulley by means of a hydromechanical drive.

When the speed of rotation of the crankshaft increases, the clutch performs light braking to prevent damage to the device. Although earlier on the first models of vases there was no such device.

Electronic. With the development of technology, an electronic drive began to be in demand. It consists of two main components - a control system and an electric motor. The use of electronics made it possible to ensure uniform cooling of the power unit and eliminate the risk of damage to the fan.

Principle of operation and design features

Each type of fan has its own design nuances and principle of operation. Let's consider each type in more detail:

1. Fan with viscous coupling. Such products are often found in models with a longitudinal installation of the power unit. At the same time, systems are mounted, as a rule, on SUVs, and with the advent of electronics, they began to gradually go out of use.

On the other hand, electronic devices are afraid of moisture, and the viscous coupling has maximum tightness and continues to work even after “bathing”.

2. Fan with ECU. Such systems consist of several structural elements - a temperature sensor, a power unit ECU and a fan switch relay. On modern cars, as many as two monitoring sensors are most often installed.

One is mounted directly in the pipe leaving the radiator, and the second is installed at the outlet of the power unit. In this case, the thermostat is activated based on the difference in the readings of these devices.

In addition, on new VAZ models, other devices, such as a crankshaft speed sensor and a flow meter, can take part in the fan control system.

In this case, all impulses are fed to the ECU, which, after analysis, gives a command to operate the device.

3. Fan with thermal switch. Old VAZ models did not have an electronic control unit, so the task of activating the device was assigned to a special thermal switch.

This device is mounted in the cylinder block housing, which allows you to clearly record the engine temperature and give a command to turn on the fan. The signal, in turn, is given due to the timely closing of the contact group of devices.

If the temperature exceeds the set limit (from 70 to 85 degrees Celsius), then the device gives a command to turn on. When the temperature drops below a certain level, a shutdown command is given.

Causes and malfunctions of the fan

During operation, the most unpredictable situations may arise. Beginners often get lost when the engine cooling fan does not work, turns on prematurely, or rotates constantly. Such problems are fraught with engine overheating or, conversely, difficulties with temperature set.

In order to fix the problem in a timely manner and prevent more serious damage, it is important to know how to check the radiator fan, and in what sequence to fix it.

As already mentioned, the temperature at which the fan turns on can vary from vehicle to vehicle. For example, on the VAZ-2110-2111, the optimum operating temperature of the power unit is about 88-89 degrees.

In this case, the fan operates at a level of 105 degrees Celsius. Further, the coolant temperature begins to decrease, and shutdown occurs at a temperature of 97 degrees Celsius and below.

Fan malfunctions and features of their elimination

1. When the fan does not start at all, you need to check the operation of the thermostat. This is easy to do - just touch the lower radiator tube on a warm engine. Cold? “Then it’s out of order and needs to be replaced.

Again, be very careful not to accidentally burn your hands. The following checks can be broken down into several steps:

Checking the fuse located in the mounting block. As a rule, he is also responsible for the sound signal of the car, so it will not be difficult to determine the presence of such a malfunction. All that is required is to press the horn. If it does not work, a new fuse must be installed.

If there are no problems with the fusible insert, then it is necessary to inspect the radiator fan relay (in the additional fuse box). In the case when the contacts of the device are stuck or it does not work even in the presence of voltage, then a replacement will be required.

Checking the fan motor. It is easy to make sure that it works - just connect the output to the battery. If it starts spinning, then the problem must be looked for elsewhere.

Examination fan on sensor. There are two main options here. If the car is carbureted, then it is necessary to close the sensor contacts (located in the radiator). If the fan has worked, then we can conclude that the sensor is faulty.

In a situation where the engine is injection, it is necessary to remove the connector from the sensor (located in close proximity to the thermostat). In this case, the fan should operate in emergency mode.

If none of the checks described above has shown itself, then it is necessary to look for an open in the secondary circuit of the car.

2. The radiator fan of the cooling system does not turn off. There are situations when the additional cooling system works and continues to work even after performing its functions (lowering the temperature).

Here are a few main reasons:

• There is a break in DTOZH or its commutation. In this case, the radiator fan is constantly running and the "Check engine" light is on. To solve the problem, it is enough to replace the sensor;
• the contacts of the relay that commands the cooling fan remain closed all the time. In such a situation, it is necessary to check the presence of voltage on the contacts of the device. If it does not arrive, and the relay is still activated, then the device will need to be replaced;
• the system control unit or one of the ECU circuits has failed. In this case, you need to go to the service station to install a new unit or flash the device;
• in a car with a carburetor engine, the contacts of the thermal switch do not open. To verify the problem, you must disconnect the wires from the terminals of the device. In this case, the fan stops working. The solution to the problem is to replace the thermal switch.

3. The radiator fan turns on early. Another type of malfunction is when the fan starts rotating before reaching the limit temperature. Here it is necessary to "sin" on the temperature sensor.

Most often, it incorrectly diagnoses the temperature regime and gives a false signal to the fan. It is important to choose the right sensor for this. Such devices are of two types - winter and summer. Each of them has its own temperature regime.

For example, winter sensors will work later, and summer ones earlier. Sometimes, with the wrong choice of device, motorists wonder why the fan turns on earlier or later. In fact, the sensor works correctly, but in its temperature range.

Many motorists underestimate the importance and usefulness of a radiator cooling fan. As a result, you can pay a serious amount from your wallet for an expensive engine repair.

So in the event of the first problems with the cooling system, it is important to diagnose the malfunction in a timely manner and fix it. Good luck on the road and of course no breakdowns.

As you know, during the operation of an automobile engine, fuel is burned. In this case, a large amount of heat is generated as part of the conversion of thermal energy into mechanical energy. At the same time, excess heat must be removed from the external environment to prevent overheating of mechanisms and parts.

The engine itself should not overheat above the optimum 80-90°C. For this, special devices are used, which in combination form. Cooling systems are also divided into two types: liquid and air. In modern cars, these two types of systems are combined and are hybrid.

Although the liquid system is considered to be the main one, air cooling deserves special attention, without which, under certain conditions, a car engine is inevitable. Let's look at the air cooling system and its malfunctions in more detail.

Read in this article

Cooling Fan Malfunctions: Symptoms and Solutions

As mentioned above, an internal combustion engine is a complex system that requires uninterrupted operation of the cooling system. Otherwise it will happen.

The liquid cooling system through which special coolants () circulate is closed. In a nutshell, the principle of operation of a liquid cooling system is that during engine operation, a liquid circulates through its shirt (channels in and), which removes excess heat from heated parts.

Then the hot liquid enters, cools down and returns to the engine again to cool it. During the passage of the radiator, the heated coolant enters a network of thin tubes. This contributes to its rapid cooling. Also, by the oncoming air flow during the movement of the vehicle, excess heat is carried out of the engine compartment of the machine.

However, if there is not enough air (when idle in traffic jams or when the engine is idling), the fluid system often does not cope with the task. Then he gets to work. In other words, an air cooling system is connected.

It is important to understand that only when these two systems interact, effective engine cooling occurs. Simply put, the fan thermal switch (fan sensor) trips and the fan turns on. As a result, an air flow is created and the fan runs until the optimum temperature is reached.

Then, having received a signal from the sensor about a decrease in temperature, the radiator fan is turned off. By the way, there is no single standard for the location of the fan installation either. It can be placed both in front of the radiator and behind it. There are also no clear standards regarding the design of the fan itself.

It consists of at least four blades, fixed together at a special angle for maximum air intake and supply. The most popular was the impeller with 8 blades. By design, the fan drive can be divided into 3 types:

• mechanical
• hydromechanical;
• electric;

Today, the first type is practically not used, especially on civilian vehicles, although it remains on powerful SUVs as the most reliable. The second type is also gradually fading into the background. In any case, if the device fails, immediate diagnostics and elimination of the cause of the breakdown is necessary.

In this case, the verification can often be carried out independently. Please note that during diagnostics, the fan may suddenly start working and its blades will seriously injure a person. Fingers are at particular risk.

Checking the cooling fan

So, if a modern fan breaks down, you need to consider that they are often electric. As a rule, the problem lies in the wiring, sensors, fuses, etc. Among the main fan malfunctions, the most common cases can be identified when the cooling fan:

1. Does not turn on.
2. Do not turn off.
3. Turns on early.
4. Directs air flow incorrectly.

You can control the operation of the fan in several ways. If the fan does not turn on, it may not have received the required signal. In this case, first of all, the entire chain of transmission of this signal is checked. To do this, using a tester, it is determined whether there is a supply voltage. If not, then the problem is a blown fuse or poor contact.

By applying voltage to the fan itself, it is its serviceability that is checked. If it spins, then the problem is not in it. If the fan does not spin, it is better to contact a car service. You can get to the service station on your own, adhering to certain rules:

• Drive at a speed of at least 60 km/h. Then the function of the broken fan will be performed by the incoming air.
• Turn on the stove to the maximum while driving, so that excess heat is removed into the cabin. It will be hot in the cabin, but the chances that the engine will not overheat increase;
• Follow the engine temperature arrow on the panel. When it approaches the red zone, you need to stop the car, open the hood, cool the engine.

When checking the temperature sensor, its wires are disconnected and closed to each other. If the problem is in it, then the fan will work. In this state, you can drive to the nearest service station for repairs. And if the fan does not work, then it most likely needs to be changed.

If the radiator fan, on the contrary, does not stop, then there are problems in the temperature sensor, shorting of the wires, or in the “sticking” of the relay contacts, when its contacts cannot open and the voltage for the fan continues to be supplied.

The reason for the constant operation of the cooling fan may also be responsible for maintaining the optimum engine temperature. When the antifreeze temperature exceeds 90°C, a special valve opens between the large and small circles of the cooling system.

If the thermostat breaks, this valve jams, the antifreeze often moves only in a small circle (without getting into the radiator for cooling). As a result, the fan will run all the time.

It is easy to identify this problem. If, when you feel the radiator hoses, they are cold, and the engine itself is hot, then the problem is in the thermostat. We add that usually jamming of the thermostat valve can be solved by tapping on its body. If this does not help, then the device must be removed and replaced.

• The fan may also turn on earlier than necessary. Most likely, this is a breakdown of the temperature sensor, which must be replaced. You also need to consider the types of sensors. They can be designed for different temperatures (the so-called "summer" and "winter" temperature sensors). They work according to the set temperature. If a "winter" sensor is used, you need to know that it is late and turns on a little later.

In this case, the fan will turn on until the overheating signal appears. It turns out that the effect of premature inclusion is created. This situation is not a violation. If the fan does not blow on the engine, but on the radiator, then it is not installed correctly. Perhaps the terminals were confused when connecting or mistakes were made. One way or another, it is necessary to make the correct reconnection of the fan.

What is the result

Having considered the features of the operation of the radiator fan, it becomes obvious that the ICE cooling system in the complex and the engine cooling fan itself make it possible to maintain the required temperature regime of the ICE.

It is also important to understand that the smooth operation of the cooling system depends on the coordinated work of all components. For example, the fan normally turns on when the engine temperature rises above 90°C to cool it, and then should turn off.

If the fan fails or does not work correctly, expensive or is inevitable when the motor overheats. At the same time, there are many reasons for failures and violations in turning on the fan, since the electronic and mechanical parts of the device often fail during operation.

However, in practice, it is often possible to independently diagnose a problematic device, identify the cause of the breakdown and, if possible, fix the problem. Finally, we note that most problems associated with engine overheating can be avoided by preventive checks, as well as regular cleaning of the cooling fan terminals and contacts.

Read also

The engine cooling fan turns on when the engine is cold or after turning on the ignition: the main causes and troubleshooting.

Any internal combustion engine requires proper cooling. Without it, the motor will simply overheat, as a result of which the moving elements will instantly fail. The engines of modern cars are equipped with a liquid cooling system, which provides for a constant cooling achieved through the operation of a water pump (pump). Whatever coolant is used in the engine, prolonged heating will invariably lead to boiling. To prevent this process, a radiator is used in the cooling system. It is a system of thin tubes equipped with special lamellas that increase the area of ​​the cooler.

When the car is in motion, the air flow enters the working surface of the radiator and passes between the lamellas, cooling the metal. Thus, the coolant temperature gradually decreases.

However, the radiator alone is unable to cope with overheating, especially if the car is stationary or moving at low speeds. He is assisted in this by an electric fan that turns on automatically when the coolant reaches a certain temperature.

If it fails, the engine will inevitably overheat with all the ensuing consequences. In this article, we will talk about the possible reasons why the cooling fan does not turn on, as well as how to identify and fix related problems.

What is a radiator fan

To begin with, we note that all the information provided is more intended for VAZ owners, although it can also be useful for drivers of foreign cars.

The VAZ cooling fan is an ordinary electric motor powered by 12 V from the vehicle's on-board network. Its shaft is equipped with an impeller that forms a powerful air flow and directs it to the working surface of the radiator. The fan on a special frame (frame) is attached to its front part. Behind it is protected by a radiator grille.

Most VAZ vehicles are equipped with one fan. But there are exceptions. For example, the NIVA cooling fan has two independent electric motors with an impeller that turn on simultaneously. This is necessary so that the engine of the domestic SUV cools faster.

How the fan turns on

Turning on the device in different models occurs in different ways. In cars with carburetor engines, it starts after the coolant reaches a certain temperature (105-107 0 C) and the fan switch-on sensor (not to be confused with the coolant) is triggered, sending a signal to the relay. It closes the electrical circuit, supplying power to the electric motor.

The cooling fan circuit for machines with an injector is slightly different. Here everything is controlled by an electronic unit. Information from the switch-on sensor is first analyzed by the controller, and only then transferred to the relay.

Possible fan malfunctions

If the liquid temperature has reached a critical level, but the radiator cooling fan does not work, then there is a problem somewhere. Our task is to find it and eliminate it. Let's denote the most common malfunctions due to which the cooling fan does not work. There are not so many of them.

1. The fan motor has failed.
2. The integrity of the wiring supplying the electric motor or connecting the fan on sensor is broken.
3. Poor contact in motor or sensor connectors.
4. cooling fan.
5. Faulty fan relay.
6. Sensor defective.
7. Violations in the operation of the safety valve of the expansion tank.

Checking the electric motor

If the cooling fan does not work, the first step is to check its drive (electric motor). Make it simple. It is enough to take two wires, connect them to the fan and power them directly from the battery. If it starts, then the problem is not in it. It needs to be looked for further. In parallel, you can check the contacts in the motor connector. Sometimes it happens that the problem is in them. The ingress of dirt and dust, as well as the oxidation of metal surfaces, can cause contact failure.

If the electric motor did not turn on after connecting to the battery, most likely it was he who broke down. The reason for this may be:

• worn brushes;
• collector destruction;
• short circuit of the rotor or armature windings.

In the first case, it is enough to replace the brushes with new ones, and the fan motor will work like new again. In the case of the destruction of the collector or the short circuit of the windings, repair may not help.

Checking the wiring

Another common malfunction that does not turn on the cooling fan is a violation of the integrity of the wiring. This may be a wire break or a short to ground. You can check the circuit using a conventional car tester turned on in detector mode. In this case, it is necessary to “ring out” not only the wire from the sensor to the controller, but also the wiring connecting the controller to the fuse, the fuse to the relay, the relay to the electric motor.

Check the fuse and fan relay

If everything is in order with the wiring, we move on to other equipment. First check the cooling fan fuse. It is usually located under the hood of a car and is labeled F7. We check it with the same car tester. If the fuse is good, move on. We are looking for a fan relay. It is located under the cover of the right panel of the center console. There are three relays. The user manual of the car will help determine the right one, since different models have different locations.

But how to check the relay? In "marching" conditions, it is almost impossible to determine its performance. It's easier to take an adjacent relay (if its parameters match) and install it in the desired slot.

Testing the fan switch

The next reason why the cooling fan does not work may be a faulty sensor. Cases of failure of this element are not so rare. It is possible to accurately determine that it is the sensor that has broken down only in a car with an injection engine. If you disconnect it from power, the electronic control unit will perceive this as a system malfunction and start the fan in emergency mode.

Verification is carried out as follows. We warm up the car until it reaches 100 0 C, after which we turn off the engine, raise the hood and turn off the sensor by disconnecting the connector on it. After that, we start the engine. If the fan turns on, then the problem is with the sensor.

Unfortunately, such a check is not possible in cars with carburetor engines. Here, you can determine the performance of the fan on sensor only by replacing it with a new one and warming up the engine to operating temperature.

Changing the safety valve

There is another malfunction that can cause the system to malfunction. If the cooling fan does not work even after confirming the operability of all the listed elements of the chain, it is worth checking the safety valve on the expansion tank.

The role of this valve is to maintain the operating pressure in the system above atmospheric pressure. This is necessary so that the water that is part of the coolant does not boil when heated to 100 0 C. If the safety valve fails, the pressure in the system will equalize with atmospheric pressure, and the liquid will boil, reaching the boiling point of water.

The switch-on sensor, as already mentioned, can only turn on at 105-107 0 C. Thus, our coolant will boil, but the fan will not work.

How to check At home, this is impossible. It's easier to buy a new valve, especially since it costs a penny.

Finally, check out some useful tips that will allow you, if not to avoid problems with the timely turning on of the cooling fan, then at least to correct the situation a little.

1. Systematically check the operation of all elements of the cooling system. Pay attention to the coolant temperature readings on the instrument panel, and also listen to see if the fan turns on.
2. Monitor the coolant level in the system. Replace it promptly.
3. Rinse the expansion tank cap under running water at least once a year. This solution will extend the life of the safety valve.
4. At the slightest malfunction in the cooling system, stop driving and take corrective action.
5. If the cooling fan does not work due to the failure of the sensor, fuse or relay, and this malfunction caught you on the way, turn off the sensor (for the injector) or connect the electric drive directly to the on-board network (for the carburetor). So you can drive to the nearest service station without the risk of overheating the engine.