We all know that when almost any mechanism operates, a certain amount of heat is generated. In everyday life, a similar phenomenon can most often be observed when the computer is running, and if it is not cooled in any way, the internal boards along with the contacts will simply melt. To prevent this from happening, the computer design includes a special fan designed to cool heated parts. IN automotive world main source of heat vehicle its engine protrudes, so the need for its cooling arose almost simultaneously with the creation of the specified power unit.

Initially, the process of evolution of vehicle cooling systems followed two paths, which is why two types of cooling systems are installed on manufactured vehicles: air and liquid (hybrid). Since in both systems the final carrier, designed to dissipate the heat removed from the engine, is air, their design uses one common element - a fan. This device ensures constant and uniform heat removal to the atmosphere, thereby cooling the internal structural elements of a car engine.

1. Design and purpose of the engine cooling fan

The fan is located in the center of a certain casing, together with which it is installed on. The fan casing forms the air flow and does not allow it to dissipate, which is why this element can be considered one of the main components of the cooling system design. During its operation, the radiator exhibits some resistance to air flow, and if you simply direct a fan at it, then a certain part of the air will be reflected and bypass the device, as a result of which there will be no effective cooling.

As we have already said, a running engine is a powerful heat emitter, and To avoid overheating of the unit itself, this heat must be removed. The solution to this problem relies on various cooling systems.

For example, in a liquid engine cooling system, water or antifreeze is used as the main working element. The fluid circulates in the cylinder block and in the cylinder head, where it takes heat from the engine, thereby heating itself. Naturally, in order to successfully perform its duties, the coolant must release the heat it receives in order to perform the same function again. This is where the radiator comes into play.

The location of the radiator of the cooling system of a car engine allows it to “catch” flows of incoming air when the car is moving, which significantly accelerates heat transfer, which means the liquid cools faster. However, a car cannot be in motion all the time, so in traffic jams or when long-term parking, when the vehicle does not move, but its engine continues to work, heat is removed from the radiator much worse, which often causes overheating of the engine with all the ensuing consequences. This result can also be obtained due to the vehicle moving at low speeds, especially on a hot summer day.

The fan located in front of the radiator prevents such situations and provides the engine with the necessary cooling. It turns on when the car is idle for a long time with the engine running, when the temperature in the cooling system becomes critical. The fan disperses the heat by passing the necessary air flow through the radiator, thereby dissipating the heat into the atmosphere.

Despite the importance of such a device, it has a fairly simple design and usually consists of three main elements: impellers(usually has four blades, but there may be more), casing And fan drive.

The fan drive, which ensures its rotation, can be of three types (on one machine, of course, only one of them is installed): mechanical, hydromechanical or electric.

Most simple option is a mechanical fan drive in which rotation is transmitted via a belt drive. But in this case, the fan always rotates when the engine is running, which in some situations (for example, when starting a cold engine) causes extremely negative consequences. Therefore, this cooling method is no longer used on cars produced today.

A hydromechanical drive is considered more advanced, which uses a hydraulic or viscous coupling for operation. In the hydraulic version of this element, torque is transmitted or disconnected from the crankshaft by changing the amount of lubricating fluid. In a viscous coupling, silicone liquid is used for this purpose, and its viscosity depends on temperature indicators, the change of which gives the command to turn the fan drive on or off. To date, both species have not found widespread distribution, which is why they can be seen infrequently.

The most advanced, and at the same time, relatively simple type of fan drive is an electric drive, which sets the fan in motion using a simple electric motor connected to the vehicle's electrical system. Thanks to an electromechanical (used on older car models) and electronic (used on new) control system, a fan equipped with an electric drive can turn on and off when the temperature of the coolant changes. Also it can rotate with at different speeds under different operating modes of the vehicle's power unit.

Nowadays, fans equipped with an electric drive type are most widely used, and this state of affairs is unlikely to change in the near future.

2. Installation and connection of the fan

Considering that cars are equipped with fans in normal mode, re-installation may only be necessary during repair work, that is, after replacing broken parts of an old part or when installing a new device. In addition, some car enthusiasts install an additional fan, which, in their opinion, can help better solve the problem of engine cooling.

Consider the option of installing a fan with electric drive in a situation complete replacement details. So, in order to install a new device, you will first have to dismantle the old one. To do this, take a suitable socket wrench and slightly loosen the electric fan mounting bolts from below. Then, using the same key, unscrew the bolts securing the radiator tube that connects it to the air conditioning system (if, of course, such is provided for by the design of the car) and move it to the side.

Next, unscrew the upper and lower (already loosened) bolts securing the old fan, tilt it back a little and remove the part from the engine compartment. Now you need to disconnect the wiring harness from the fan casing. To do this, simply remove the wire harness from the clips located on the casing. While holding the impeller from turning (you can use any convenient method), unscrew the nut securing it to the electric motor with a socket wrench, then, freeing it from the connection with the casing, simply remove it.

Installation of the new part is carried out in the reverse order, and most often the electric fan is replaced assembled with a new casing. Pay attention! When installing the impeller on the axis of the electric motor, you need to align the groove located on the axis of the electric motor with the protrusion located on the hub of the impeller.

The fan can be connected in several ways: for example, through the ignition switch or through the coolant temperature sensor. In these cases, it should turn on when the ignition is turned on and when the antifreeze temperature is above 90 ° C, and the shutdown occurs either due to a decrease in the temperature of the specified fluid or when the ignition is turned off. Also, in parallel with the temperature sensor, some car owners recommend installing an additional switch (toggle switch), with which you can activate the fan at the driver’s request. If the temperature sensor breaks down, such an addition will help you get to the repair site without any problems, and in hot weather it will provide the opportunity to cool the engine in conditions of forced downtime with the engine running.

3. Refinement of the fan motor switching circuit

Many responsible car enthusiasts can spend hours in the garage, trying not only to fix existing problems, but also to prevent the occurrence of new problems through various improvements and modifications. The main goal of refining the electric fan switching circuit is to be able to forced inclusion and subsequent stable operation of the fan, regardless of the position of the key or the temperature of the cooling liquid.

There are several ways to complete this task. Let's give an example of some of them. The first method is the most ideologically correct and least expensive. In this case, to force the engine cooling fan to turn on, it is enough to short-circuit one of the contacts of the black box to the housing, and when the radiator fan is activated, a “plus” should appear on the other contact of the black box.

The switch can be placed in any convenient place, for example, instead of the headlight washers or heated front seat switches.

The second method is more labor-intensive and expensive, but at the same time much more beautiful and elegant than the first. To implement it, at the initial stage it will be necessary to remove the instrument cluster trim, and a new fan switch relay, which has a special bracket for mounting the device, can be placed in the passenger compartment or in engine compartment, but the cabin will probably be a little more comfortable. Running wires into the interior is not a problem, and you can use the rubber plug for the headlight range control to complete the task. Ideal for the role of a fan indicator light warning lamp"CHECK ENGINE" gearbox, and a diode soldered between them will help protect the contacts of the switching sensor from electromotive force (EMF).

To ensure that the circuits of the electric motor and the windings of its relay are protected by a fuse, a jumper is installed in the black box between the contacts, the material for which can be, for example, two male terminals and a piece of thick copper wire. Upon completion of work, all contacts should be treated with special lubricant.

In addition, when performing such modifications, it would be useful to clean and lubricate the fan motor, and if you also replace the standard impeller with four blades with a part with eight blades, then the air flow passing through the radiator will increase significantly, which means the quality of cooling should improve.

We briefly described only two options for refining the circuit for switching on an electric radiator fan, but this is far from a final figure, because everything depends on the imagination of the car owner and the capabilities of his vehicle.

Construction and circuit diagram radiator fan may differ not only depending on the make of the car, but also on the year of manufacture and model configuration. Let's consider not only the principle of operation, but also the connection option with the possibility of forced activation of the cooling system fan (VSO).

Cooling system design features

Depending on the design features, the fan can be turned on in 3 ways:

• using a power sensor for activation of the VSO. This sensor is also called a fan temperature relay, since the power contacts of the electric motor pass directly through the sensor. With this scheme, the load on the thermal relay increases significantly, which reduces its service life;
• using the fan switch sensor, but now closing the contacts in the temperature switch triggers the relay, through which the power contacts of the cooling system fan are connected. This connection method is much more reliable than the previous option;
• using an electronic engine control unit. The ECU, focusing on the coolant temperature sensor installed in the engine cooling radiator, supplies power to the VCO through a relay. A resistive temperature sensor is used as a meter. It is this switching scheme that is used in the vast majority of modern cars. On cars equipped with air conditioning, one of the electric fans will be controlled by the comfort unit. This is necessary for forced cooling of the condenser when the interior air conditioning system is activated.

Operating modes

When understanding the operating principle and connection diagram of the radiator fan, you should remember that electric motors often have two speed limits. This is implemented in 2 ways:

• by adding a resistor to the circuit, which increases the resistance and, as a result, reduces the current. The design uses a two-contact sensor, which, depending on the temperature, powers the electric motor directly or through resistors;
• combination of parallel and sequential connection. The circuit is used on a car with two fans. They can be connected in series, in which case, according to Ohm's law, they will operate from 6 V, or in series, when 12 V is supplied to each of the VSOs. The modes correspond to low and high speed propeller rotation.

Scheme options

Schematic diagram of VSO connection on VAZ 2108, 2109, 21099 (until 1998).

As we can see, the sensor controls the fan relay, which is located in the fuse box. When a certain temperature is reached, the contacts of the temperature switch close, which leads to the flow of current in the electric motor circuit.

Above is a diagram for VAZ 2108, 2109, 21099 cars, but after 1998. As we can see, the power sensor now functions as a relay.

Let's consider a circuit using a resistor to implement two propeller rotation speeds using the VW Passat as an example. The two-position fan power sensor S23, depending on the coolant temperature, closes the contacts directly or through an additional resistance.

DIY connection

Some drivers, warning the engine against malfunction of the radiator fan power supply thermal relay, make a remote button to force the electric motor to turn on. To do this, it is enough to connect a fixed button in parallel to the control output of the relay coming from the sensor, which, when pressed, will close the contact to ground, thereby provoking the operation of the relay. If the car's design does not provide a fan relay, you will have to install it yourself to force cool the radiator.

Under no circumstances connect the electric motor directly through the button in the cabin! We also do not recommend connecting the circuit so that after turning on the ignition the electric fan constantly rotates, as this significantly reduces its service life.

To connect, you only need an understanding of the operating principle of a 4-pin relay and minimal knowledge of installation additional equipment. Be sure to include a fuse of the required rating in the power circuit and place it as close to the power source as possible (read more).

If desired, you can replace the single-position sensor with a two-position one, which, paired with a selected resistor, will allow you to realize a low speed of operation of the VSO. If you have a sufficient level of knowledge in electrical engineering, then you can build a PWM controller to adjust the speed of rotation of the propeller. Controlling the electric fan using a PWM signal will allow you to smoothly regulate and arbitrarily select the rotation speed depending on the temperature load on the engine. There is enough material on the Internet on how to make a PWM controller with your own hands.

If the fan itself on your car does not work, then carefully check all of the above components of the cooling system. However, there are times when one situation will not be related to the breakdown in question.

Fuse

Problems with the electrical circuit

If checking the reservoir cap does not reveal any faults, then the problem may lie in the circuit.

The search should begin by checking the serviceability of fuse F7. To do this, you need to gain access to the mounting block and check the contacts for the presence of oxidative traces. If nothing of the sort was noted, then proceed to the next step. Otherwise, clean the contact connections or simply replace the fuse with a new element. The part is inexpensive.

The next step is to check the fan switch sensor:

1. Initially, warm up the car to 100 degrees.
2. Turn off the engine and immediately start the engine.
3. Open the hood and disconnect the terminal from the fan sensor.
4. If, after disconnecting the contact, the fan starts working, then the unit is operational, but the sensor needs to be replaced.
5. When the fan does not turn on after disconnecting the terminal, then the situation is the opposite - the sensor is working, but the fan is not.

Electric motor breakdowns are often the reason why the fan does not turn on. If all the previous measures did not help you find the problem, then you will need to dismantle the electric motor. The following problems can be identified in this node:

1. The commutator brushes are worn.
2. The brushes are stuck.
3. Was short circuit on the armature winding - the problem is determined by the characteristic smell.

Problems with the relay. Sometimes a situation arises when the cooling system fan start button simply fails. In this case, you will need to carry out the following work:

1. Remove the trim on the right side of the dashboard inside the passenger compartment. To do this, you need to unscrew two screws.
2. Under this panel there are three relays.
3. The required relay is usually located on the side in relation to the front of the car.
4. To be sure to act correctly, find the car's operating manual and check the wires that go to the relay we need.
5. To solve the problem with the relay, you just need to install a new element. You should not skimp on this component. Cheap models break down very quickly.

What to do when the fan runs constantly

There are situations when the cooling radiator works without interruption, both hot and cold. cold engine. The reasons can be very different. Now we will look at the main problems and ways to solve them.

1. A break in the sensor that monitors the antifreeze temperature readings or its circuits. In this case, it lights up Check light engine. The circuits and sensor are checked with an ohmmeter. The problem is solved by replacing the element with a new one.
2. The fan relay contacts open. First, the component is checked with a multimeter and, if necessary, replaced with a new one.
3. Malfunctions in the ECU. Check this node on the profile service. If a malfunction is detected, the firmware or the unit is changed completely.
4. In VAZ carburetor models, the thermal switch contacts do not open. To check operation, disconnect the terminals from the terminals of this unit - and the fan will stop. In this case, it is necessary to replace the faulty part.

If the tests carried out have not determined why the fan is constantly running, then the only possible way out of the situation is to contact a service center.

Full-fledged service stations, as a rule, conduct a full computer check of the cooling system, which can identify the most difficult to detect faults. The failure can be much more global than a normal fuse failure.

If the usual testing steps do not produce any results, then you should not be afraid to contact the service, and even in cases where you consider yourself an experienced technician. Often, modern equipment and a professional approach significantly reduce the troubleshooting time. Whereas conventional methods would take weeks to determine the problem. Therefore, car services have their own advantages.

The radiator fan is one of the main elements of the engine cooling system. His role is forced airflow radiator when the coolant is heated to a certain temperature.

Unlike carburetor engines, injection engines VAZ 2110 the fan is turned on not directly from the temperature sensor, but through electronic unit control unit (ECU). The sensor is installed on the outlet pipe of the cylinder head.

When the coolant heats up to a temperature of 100-107 0 C, the sensor is triggered and sends a signal to the ECU, which processes it and sends it to the relay. The relay closes the circuit and supplies power to the drive ( electric motor) fan via fuse.

Reasons why the fan may not turn on

Considering the described switching process, the reasons for the fan not working may be:

• faulty temperature sensor;
• faulty relay;
• blown fuse;
• break electrical circuit;
• Problems with the electric fan drive.

In addition, the cover can also affect the timely switching on of the fan. expansion tank. If it is faulty and its valve is not capable of maintaining pressure above atmospheric pressure, the water that is part of the coolant will definitely boil at 100 0 C, and the sensor set to more high temperature, will not have time to work.

How to check the fan circuit

1. We start the test with the simplest thing - determining the state of the fuse. We are looking for it in the mounting block, which is located under the hood. Its marking is F7.

2. We take it out, and visually, or using a multimeter, check for functionality. If it burns out, replace it with a new one (20 A). If everything is fine with him, we put him in his place and move on.

3. In order not to waste time, it is better to immediately determine the performance of the fan motor. To do this, disconnect the wires from it and connect it directly to the battery, observing the polarity. If the fan is “alive”, we continue to look for the cause.

4. Move on to the fan relay. It is located in an additional mounting block in the car interior to the left of the front passenger's feet.

5. There are three relays there. Ours is on the far left.

It is unlikely that you will be able to check it yourself; it is better to take another one somewhere and put it in the place of the person being checked. We heat the motor to maximum temperature and observe the behavior of the fan. If there is no result, move on.

Unscrew and inspect the cap of the expansion tank. At the slightest suspicion of leakage, throw it away and install a new one.

Next we move on to the sensor itself. We start the engine, heat it to a temperature of more than 100 0 C, and disconnect the connectors from the sensor. The ECU that controls the operation of the sensor should automatically send a signal to the relay to force the fan to turn on. If the fan turns on, the problem is most likely in the sensor. We replace the sensor with a new one and check its operation.

If nothing works here, you need to look for an open circuit in the electrical circuit. To do this, it is better to contact specialists.

This solution allows you to get rid of frequent startups cooling fan, there are no voltage drops (although I didn’t have any due to a good generator and an automatic LV at 14.5V), the idle voltage does not drop when the fan is turned on. And there is no vibration in the body with the original 4-blade fan. The normal operation of the cooling fan remained in place.

The cooling fan now turns on at half power at a temperature of 92 degrees, and maximum speed will be when it reaches 96 degrees.

This is what happened:

Just like that in the engine compartment. There is a tee in the center, a relay on the left, etc.

For this we needed the following components:

1… Tee for a cooling sensor from a gazelle, costing 150 rubles. Sawed by a Bulgarian's wife and rolled with a hammer and filed.
2… DTOZH from the classics 92/87 degrees. 100 rubles.
3… 2 clamps for the pipe. What size - I don't know. Just under this pipe and that’s it...
4… Relay 4-pin 70 A + connector. Cost 160 rubles with chip.
5… 30 A remote fuse. I installed a 30 pin relay in the power circuit.
6… There were crimping chips + crimping (you can also use narrow pliers) and heat shrinking.
7… Various wires 4 meters.
8… Mother/father chips for the fan, because I didn’t want to cut the insulation. The “original” fan chip is disconnected, our purchased one is connected to each other, the positive contact is isolated, and the negative contact is used to connect the signal from the relay to it.
9… Resistance from a classic stove is 1.5 ohms. You can put a resistance of 2-2.5 Ohms, but I couldn’t find the resistance from the UAZ stove in my city. So we are content with what we have. The fan is supplied with 6.6 V according to the tester.

The lower radiator pipe is cut if your radiator is a new model without a plug for the DTOZH. Place the tee so that the sensor contacts are at 90 degrees, and not like in my photo (I slightly missed at the moment, the stove body does not sit down as it should). But this will be corrected when replacing the coolant.
If you have an old-style radiator, or a Luzarovsky universal one, then you do not need to cut the pipe. These radiators have a plug for the DTOZH.

And here is the scheme of work.

87… We twist the contact or solder it to the black wire of the fan (focus on the wires from the fan itself, and not on the central wiring, because the colors may differ. Another option is to call with a multitester). “Plus” is supplied to the fan permanently, but it is controlled by a mass signal (it may differ depending on the year of manufacture judging by the comments).
86… the contact can be connected directly to the “positive” terminal of the battery. The relay winding does not draw voltage.
85… We connect the relay contact into the gap through the coolant temperature sensor (DTOZH). The sensor in our case acts as an automatic button.
30… We connect the contact directly to the negative terminal of the battery through a fuse, then we connect a resistance resistor and then to the relay.

The resistance resistor itself was pulled to the cooling fan housing with a regular clamp. Mount the resistor in the area of ​​the air flow from the fan to cool it. It heats up well during operation.

In general, everything... During the entire evening of active driving and traffic jams, the fan never turned on fully. Everything is automatic, there are no surges or drops in rpm at idle. I like. The fan continues to run briefly even after the ignition is turned off.

Also in this diagram without any problems, you can add a button for forced activation of the fan - be sure to use a relay, take the control plus of the relay coil (pin 85 for example) from the main relay from the passenger compartment, control minus (pin 86) through the fan switch button, connect the DTOZh contacts to pins 30 and 87. All this is necessary so that the fan turns off when the ignition is turned off and eliminates the possibility of constant operation of the fan in case of forgetfulness of the driver.
Although IMHO this button is superfluous with this solution.

Well, by the way, this scheme can also be used for carb cars. You just need a sensor, one “chisel” for the radiator, and the second “classic” for the tee (although it can be done the other way around). Well, that is if you can’t find a 2-mode fan switch sensor from a foreign company.

P/S.. We installed the same for a friend on a VAZ 2115, 2006. - according to the diagram, it was necessary to change the polarity of the voltage supply to the fan. It is controlled not by “minus”, but by “plus”.