Sensor for turning on the fan VAZ 2107 carburetor. Fan off sensor: features and installation

All the main wiring diagrams and modifications of the connection of the cooling fan (CO) of the liquid in VAZ cars of various models are given. What is the essence of the work of VO? An electric motor with an impeller on a shaft is mounted inside a rectangular metal frame, with which it is attached to the back of the radiator. When voltage (12 V) is applied to the drive contacts, it starts to work, rotating the blades and creating a directed air stream, which, in fact, cools the antifreeze or antifreeze.

If the cooling fan does not work, do not rush to contact a car service. You can determine the cause of the malfunction yourself. Moreover, for this it is not at all necessary to have special skills - just study the reference material from website and follow the instructions for checking/replacing it.

Scheme of switching on the cooler VAZ 2104, 2105 and 2107

1. radiator fan
2. temperature sensor (located on the bottom of the radiator)
3. mounting block
4. ignition relay
5. egnition lock

A - to the contact "30" of the generator.

Electric cooling fan VAZ 2106

1. motor start sensor;
2. fan motor;
3. motor start relay;
4. main fuse block;
5. ignition switch;
6. additional fuse block;
7. generator;
8. accumulator battery.

Fan connection 2108, 2109, 21099

Until 1998, on cars with the old fuse block 17.3722 (finger-type fuses), relay 113.3747 was included in the fan circuit. After 1998 there is no such relay.

Also, until 1998, the switch-on sensor TM-108 was used (the temperature of closing its contacts is 99 ± 3ºС, opening 94 ± 3ºС), after 1998 TM-108-10 with similar temperature ranges or its analogues from different manufacturers. The TM-108 sensor works only in tandem with a relay; the TM-108-10 reinforced for high current can work both with and without a relay.

Scheme of switching on the engine cooling fan on the VAZ 2109 with mounting block 17.3722

1. Fan motor
2. Motor enable sensor
3. Mounting block
4. ignition switch

K9 - Relay for turning on the fan motor. A - To the output “30” of the generator

Scheme of switching on the engine cooling fan on the VAZ 2109 with mounting block 2114-3722010-60

1. Fan motor
2. The sensor 66.3710 of inclusion of the electric motor
3. Mounting block

A - To the output “30” of the generator

Scheme of inclusion of VO VAZ 2110

The scheme for switching on the VAZ 2110 cooling fan on carburetor and injection cars is different. On cars with a carburetor engine, a TM-108 thermobimetallic sensor is used for this, and on cars with an injection engine, the control is carried out by the controller.

Scheme for 2113, 2114, 2115 injector and carburetor

Where is the fan relay

4 - electric fan relay;
5 - relay of the electric fuel pump;
6 - main relay (ignition relay).

Attention: the sequence of relays and fuses can be arbitrary, we are guided by the color of the wires. Therefore, we find a relay from which a thin pink wire with a black stripe extends, coming from the main relay (terminal 85 *) (not to be confused with a thin, red wire with a black stripe coming from the controller) and a thick power white wire with a black stripe (terminal 87) (white and pink wires we need), this is the fan relay.

If the cooling fan is not working

To drive the fan, a DC electric motor with excitation from permanent magnets ME-272 or similar is installed. Technical data of the electric fan and the fan switch-on sensor:

• Rated speed of the motor shaft with impeller, 2500 - 2800 rpm.
• Consumed current of the electric motor, 14 A
• Sensor contact closure temperature, 82±2 deg.
• Opening temperature of the sensor contacts, 87 ± 2 degrees.

The cooling fan may not turn on due to:

• malfunctions of the electric drive;
• blown fuse;
• faulty thermostat;
• a failed temperature sensor for turning on the cooler;
• faulty VO relay;
• breakage of electrical wiring;
• defective expansion tank cap.

To check the VAZ fan motor itself, we apply 12 V voltage from the battery to its outputs - a serviceable motor will work. If the cause of the problem is the fan, you can try to repair it. The problem is usually the brushes or bearings. But it happens that the electric motor fails due to a short circuit or a break in the windings. In such cases, it is better to replace the entire drive.

The fuse VO is located in the mounting block of the engine compartment of the car and has the designation F7 (20 A). The check is performed using a car tester turned on in probe mode.

1. In a car with a carburetor engine it is necessary to check the sensor - turn on the ignition and close the two wires leading to the sensor. The fan should turn on. If this does not happen, the problem is definitely not in the sensor.
2. For injection cars it is necessary to warm up the engine to operating temperature, and disconnect the sensor connector by disconnecting it from the on-board network of the machine. In this case, the controller must start the fan in emergency mode. The electronic unit perceives this as a failure in the cooling system, and forces the fan drive to work continuously. If the drive starts, the sensor is faulty.

Replacing an electric fan in a car

1. We put the car on a flat surface, immobilize it with a parking brake.
2. Open the hood, disconnect the negative terminal.
3. With a 10 key, unscrew the fasteners of the air filter housing.
4. Using a screwdriver, loosen the air duct clamp on the air flow sensor and remove the corrugation.
5. We unscrew the screws that fix the cover of the air filter housing, remove the filter element.
6. Using an 8 key, unscrew the air intake mount and dismantle it.
7. With a key of 10, then by 8 we unscrew the nuts securing the fan casing around the perimeter (6 pieces in total).
8. Disconnect the wiring harness at the fan connector.
9. Carefully remove the fan shroud along with the drive.
10. Using a 10 key, unscrew the 3 bolts holding the electric motor to the casing.
11. We put a new one in its place.
12. We install the structure in place, fix it, connect the connector.
13. Further installation is carried out in the reverse order.

Control circuit upgrade

The cooling fan on the top ten turns on at a temperature of 100-105 ° C, while normal operating
The temperature of the engine is 85-90°C, it turns out that the fan turns on when the engine overheats, which naturally has a negative effect.

This problem can be solved in two ways: adjust the turn-on temperature in the "brains" or make a button. We will focus on the second. Turning on the fan from the button is very convenient: got into a traffic jam - turned it on, left - turned it off, and no one overheated.

A button for selecting the fan operation mode was installed in the cabin (permanently turned off, always on, turned on automatically by means of a sensor) - this “tuning” is not mandatory, but it will be a very useful addition.

There will be a large current on the relay contacts 87, 30, on the wire from the battery to the fuse and the fan ground, and therefore we must use wires there with a cross section of at least 2 mm, otherwise the thinner wire will not withstand and burn out.

Video - connecting and checking VO

VAZ 2107 is equipped with an electric radiator cooling fan. It automatically turns on when the coolant is heated to 90 degrees and under normal conditions ensures a stable engine temperature, regardless of air temperature and driving mode.

But there is one problem. Sometimes the relay (sensor) for turning on the fan breaks down and radiator fan VAZ 2107 does not start. As a result, the engine overheats and the matter, at best, is limited to boiling and leakage of coolant, and at worst, an overhaul of the engine. To avoid problems, you can improve the design by organizing forced airflow to the radiator. There are two ways to do this: mechanical and electrical.

Mechanical forced cooling of the radiator VAZ 2107

On older VAZ models, the radiator was cooled by an impeller mounted on the water pump rotor. This solution provided a constant cooling of the radiator when the engine was stuck. Considering that the design of the VAZ 2107 differs little from its "predecessors", it will not be difficult to install such an impeller.

The advantage of such a solution is reliability. Forced mechanical cooling of the radiator ensures that the car does not boil while standing in a traffic jam on a hot day. But at the same time, the efficiency of blowing at low speeds is reduced in comparison with electric blowing. In winter, another drawback of forced cooling manifests itself - a cold engine is additionally blown by a fan, which slows down its warming up a little. The fact that the fan blows over the radiator on a cold engine does not affect the warm-up rate in any way, provided the thermostat is running. The fact is that before the engine warms up, the coolant circulates along a small circuit, bypassing the radiator.

The mechanical drive of the VAZ 2107 cooling fan can be improved:

• Install a diffuser that directs air flow through the radiator honeycombs. This will improve the cooling efficiency.
• Move the radiator a little back, closer to the impeller. To do this, you can tilt its upper part, using hard steel straps for fastening. The slats must be calculated so that the distance between the radiator and the impeller is approximately 2040 mm.

Thus, you can protect the car from overheating.

Electric radiator cooling fan (forced)

So that a breakdown of the VAZ 2107 fan sensor does not bring problems, forced cooling can be arranged without replacing the standard electric fan with an impeller put on the pump pulley. To do this, it is enough to provide a backup switch on the fan with a button. You will need the following parts and materials:

You will also need a new fan sensor if the old one is faulty. You can check the serviceability with an ohmmeter or continuity. If the fan does not turn on when the lower part of the radiator heats up, it must be changed.

First you need to reduce the current passing through the contacts of the thermal relay that controls the fan on. To do this, the VAZ 2107 fan switching circuit must be changed so that it is not powered directly from the sensor, but through an additional relay. In this case, the contacts of the fan sensor (thermal relay) will not burn out, and in the event of an additional relay failure, it will be much easier to replace the latter.

It is also necessary to connect the fan on button so that when turned on, it duplicates the sensor, applying voltage to the relay coil when turned on. In this case, if the sensor breaks down, it will be possible to manually turn on the VAZ cooling fan and protect the engine from overheating.

Improving the cooling system with an electric fan

To improve cooling, you can replace the standard VAZ 2107 cooling fan with a more powerful and advanced one. In this capacity, fans from viburnum or priors are suitable. The eight-bladed fan is particularly efficient, providing particularly strong airflow.

It is worth considering that the VAZ 2107 cooling system was originally designed for efficient operation. If it does not cope, the reason lies not in an inefficient standard battery, but in clogged radiator cells or a lack of coolant in the system. Therefore, in case of engine overheating with the fan running, it is worth checking the coolant level and cleaning the radiator cells (or replacing it).

On a VAZ 2107 car, as on a representative of the VAZ "classics", there is a rather loud cooling fan. The moment of its connection cannot be missed in any way. The vibration of the body increases, a rumble is heard from under the hood, if the turn-on time coincided with an increased load on the power supply (flashing turn signals when the low beam is on, rear window heating) - then the load arrow on the power supply begins to slide into the red zone.

And even, (with poor carburetor adjustment), the emergency oil pressure lamp may start to burn.
The cooling scheme of the VAZ 2107 is such that under normal conditions the fan does not turn on immediately, but only after reaching a certain temperature in the system. To determine this “convenient temperature moment”, there is a sensor, or a fan on / off controller.

The location of the controller on the radiator is not accidental: after all, at first the "small circle" of antifreeze is heated, then the cooling circuit provides for the passage of liquid through the radiator, whose work consists in intensive heat exchange. And only when the temperature rises above 92 ° C, the fan switch-on sensor is activated.

About forcibly turning on the fan

The cooling scheme does not provide for the fan to be constantly running. But in some cases, the principle of "forced connection of the fan" can be implemented.

This is done if the sensor is out of order, and replacement on the way is not possible. You can check this as follows: the engine temperature controller already showed the vertical position of the arrow on the dial, it persistently “climbs” into the red zone, and the fan is silent, it does not turn on. If so, then there are likely two possible reasons:

• The sensor itself has failed, which turns on the fan of the VAZ 2107 car. This situation is more favorable than that described below. Firstly, the cooling circuit is complete, and the radiator is working properly. This means that most of the heat is removed. There are two ways out of this situation, the following scheme of action is proposed:

1. If there is a straight road ahead and the car will move without stopping, then you can follow the temperature scale. In case of traffic jams, traffic lights, you can - turn on the stove at full power at double the blowing speed.
2. You can decide on the installation of forced switching on of the fan. To do this, two contacts are pulled out of the controller, and short-circuited together. Attention! Before that, you must first remove the "minus, ground" from the battery. After the wires are short-circuited, the negative terminal is reconnected, and the Carlson starts to work constantly, regardless of the engine temperature and the vehicle's driving mode. After stopping the VAZ 2107, the fan will run until the battery is discharged, so after stopping, you need to open the hood and remove the negative terminal.

This is very annoying for owners of a VAZ 2107 with a central lock and an alarm, so you can disconnect the fan wires, however, then they need to be reconnected and insulated. You also need to find a place for them in the engine compartment so that they do not fall under the working impeller blades, because the layout of all wires in the engine compartment is supposed to be in harnesses. Of course, it is inconvenient to drive for such a long time, because constantly opening - closing the hood to connect - turn off will get tired. In addition, constant noise, vibration and increased wear on the fan shaft bearings will not please anyone either. Forced activation is an emergency method.

The sensor that turns on the fan is such a capricious thing that costs a penny, and self-replacement along the way is problematic, since you need to drain the antifreeze.

• The second reason is more dangerous: the thermostat failed, and the engine cooling circuit became incomplete - the radiator did not turn on. Naturally, when the radiator is empty, the sensor does not respond, and the fan on the VAZ 2107 does not turn on. Its danger is that heat transfer is many times worse, since the heat exchanger of a huge total surface - the radiator - does not work. The only salvation is the inclusion of the stove at full power, and the periodic stops of the VAZ 2107, which prevent the arrow from moving into the red zone.

How to check if the new controller is working

It is necessary to take an accurately graduated thermometer capable of operating at the boiling point of water;

• Place the part of the controller facing the inside of the radiator into the water;
• Connect the tester probes to the contacts and adjust them for the disappearance of resistance;
• When water is heated, resistance disappears in the temperature range from 87 to 92 degrees Celsius. Everything, the sensor is working, replacement and switching on will be successful.

How to remove / install a new sensor

After purchasing and checking the controller, you need to do the following.

Forced airflow of the cooling radiator is used in all automotive internal combustion engines without exception. This is the only way to avoid overheating of the power plant. That is why it is necessary to periodically check the health of the electrical circuit for turning on the radiator fan.

Cooling fan VAZ 2107

In the power plants of the first "sevens", the radiator fan was installed directly on the water pump shaft. Like the pump, it was driven by a belt drive from the crankshaft pulley. This design was also used on other vehicles at that time. It almost never failed, and it was impossible to overheat the engine with it. However, she had one drawback. The constantly cooled power unit warmed up very slowly. That is why AvtoVAZ designers changed the principle of forced airflow, replacing a mechanical fan with an electric one, moreover, with automatic switching on.

Why do you need an electric fan

The fan is designed for forced airflow of the cooling radiator. During the operation of the power plant, the liquid refrigerant through the opened thermostat enters the radiator. Passing through its tubes, equipped with thin plates (lamellas), the refrigerant cools down due to the heat exchange process.

When the car is moving at speed, the oncoming air flow contributes to heat transfer, but if the car is stationary for a long time, or drives slowly, the coolant does not have time to cool down. At such moments, it is the electric fan that saves the engine from overheating.

Device design

The radiator fan consists of three main elements:

The motor rotor is equipped with a plastic impeller. It is she who, rotating, creates a directed air flow. The engine of the device is installed in a metal frame, with which it is attached to the radiator housing.

How an electric fan turns on and works

The process of turning on the fan for carburetor and injection "sevens" is different. For the first, a mechanical temperature sensor mounted in the lower part of the right tank of the cooling radiator is responsible for its inclusion. When the engine is cold, the sensor contacts are open. When the temperature of the refrigerant rises to a certain level, its contacts close, and voltage begins to be applied to the brushes of the electric motor. The fan will continue to operate until the coolant cools down and the sensor contacts open.

In the injector "sevens" the electric fan switching circuit is different. Here everything is controlled by an electronic control unit. The initial signal for the ECU is information coming from a sensor installed in the pipe leaving the engine (near the thermostat). Having received such a signal, the electronic unit processes it and sends a command to the relay responsible for turning on the fan motor. It closes the circuit and supplies electricity to the electric motor. The unit will continue to operate until the temperature of the refrigerant drops.

In both carburetor and injection "sevens", the electric fan circuit is protected by a separate fuse.

Fan motor

The electric motor is the main unit of the device. The VAZ 2107 used two types of engines: ME-271 and ME-272. According to the characteristics, they are almost identical, but as for the design, it is somewhat different. In the ME-271 engine, the body is stamped, i.e., non-separable. It does not need periodic maintenance, however, in the event of a malfunction, it can only be replaced.

The device and characteristics of the fan motor

Structurally, the motor consists of:

• corps;
• four permanent magnets glued around the circumference inside the case;
• anchors with winding and collector;
• brush holder with brushes;
• ball bearing;
• support sleeve;
• back cover.

The ME-272 electric motor also does not need maintenance, but unlike the previous model, if necessary, it can be partially disassembled and attempted to be restored. Disassembly is carried out by unscrewing the coupling bolts and removing the rear cover.

In practice, repair of the electric fan is impractical. Firstly, you can only buy used spare parts for it, and secondly, a new device assembled with an impeller costs no more than 1,500 rubles.

Table: main technical characteristics of the electric motor ME-272

Cooling fan malfunctions and their symptoms

Given that the fan is an electromechanical unit, the operation of which is provided by a separate circuit, its malfunctions can manifest themselves in different ways:

• the device does not turn on at all;
• the electric motor starts, but runs constantly;
• the fan starts running too early or too late;
• during operation of the unit, extraneous noise and vibration occur.

The fan does not turn on at all

The main danger posed by the breakdown of the cooling fan is overheating of the power plant. It is important to control the position of the arrow of the temperature indicator sensor and feel the moment the device is turned on. If the electric motor does not turn on when the arrow reaches the red sector, most likely there is a malfunction of either the device itself or its circuit elements. These breakdowns include:

• failure of the armature winding, wear of the brushes or motor collector;
• sensor malfunction;
• break in the electrical circuit;
• fuse blown;
• relay failure.

Continuous fan operation

It also happens that the motor of the device turns on regardless of the temperature of the power plant and works constantly. In this case, there may be:

• short circuit in the electric circuit of the fan;
• sensor failure;
• jamming of the relay in the on position.

The fan turns on early, or, conversely, late

Untimely turning on of the fan indicates that the characteristics of the sensor have changed for some reason, and its working element reacts incorrectly to temperature changes. Similar symptoms are typical for both carburetor and injection "sevens".

Extraneous noise and vibration

The operation of the cooling fan of any car is accompanied by a characteristic noise. It is created by an impeller, cutting through the air with its blades. Even merging with the sound of the car engine, in the "seven" this noise is clearly audible even from the passenger compartment. For our cars, it is the norm.

If the rotation of the fan blades is accompanied by a hum, creak or whistle, the front bearing or the support sleeve in the cover may have become unusable. A crack or knock indicates the contact of the impeller with the inner edge of the frame in which the electric motor is installed. Such a malfunction is possible due to deformation or misalignment of the fan blades. For the same reasons, vibration occurs.

Diagnostics and repair

It is recommended to check the fan and its electrical circuit elements in the following order:

1. Fuse.
2. Relay.
3. Electric motor.
4. Temperature sensor.

Checking the functionality of the fuse

The fuse is usually checked first, as this process is the easiest and does not take much time. For its implementation, only an autotester or a test lamp is required. The essence of diagnostics is to determine whether it passes an electric current.

The fan circuit fuse is installed in the vehicle's mounting block, which is located in the engine compartment. In the diagram, it is designated as F-7 with a rating of 16 A. To check and replace it, you must perform the following work:

Relay Diagnostics

As we have already said, in the injection "sevens" a relay is provided to unload the electrical circuit of the radiator fan. It is installed in an additional mounting block located under the glove box in the passenger compartment and is designated as R-3.

Checking the relay yourself is quite problematic. It is much easier to take a new device and install it in the place of the diagnosed one. If the electric fan turns on when the refrigerant is heated to the desired temperature, then the problem was precisely in it.

Checking and replacing the electric motor

Required tools:

• voltmeter or multifunctional autotester;
• two pieces of wire;
• socket wrenches on "8", "10" and on "13";
• pliers.

The order of work is as follows:

1. Disconnect the fan power connector.
2. We connect two wires to the contacts of the half of the connector that comes from the electric motor, the length of which should be enough to connect them to the battery terminals.
3. Connect the ends of the wires to the battery terminals. If the fan does not turn on, you can prepare to replace it.
4. If it has worked properly, it is worth checking whether voltage is applied to it.
5. We connect the voltmeter probes to the contacts of the other half of the connector (to which voltage is applied).
6. We start the engine, close the sensor contacts with a screwdriver (for carburetor cars) and look at the readings of the device. The voltage at the contacts should be equal to what the generator produces (11.7–14.5 V). For injection machines, nothing needs to be closed. It is necessary to wait until the engine temperature reaches the value at which the electronic control unit sends a signal to the relay (85–95 °C) and read the instrument readings. If there is no voltage, or it does not correspond to the set values ​​\u200b\u200b(for both types of motors), the cause should be sought in the device circuit.
7. If a malfunction of the electric motor is detected, using the “8” socket wrench, unscrew 2 bolts fixing the fan shroud to the radiator (left and right).
8. Carefully pull the casing towards you, at the same time releasing the sensor wires from the retainer.
9. Using pliers, we compress the petals of the wire sheath. We push the clamps out of the casing.
10. Dismantle the fan assembly.
11. Holding the impeller blades with your hand, unscrew the nut of its fastening with a socket wrench to “13”.
12. Disconnect the impeller from the shaft.
13. Using the key to "10", unscrew all three nuts that secure the motor housing to the frame.
14. We remove the faulty electric motor.
15. We install a new device in its place. We assemble in the reverse order.

Diagnostics and replacement of the temperature sensor

The temperature sensors of carburetor and injection "sevens" differ not only in design, but also in the principle of operation. For the former, the sensor simply closes and opens the contacts, while for the latter, it changes the value of its electrical resistance. Let's consider both options.

carbureted engine

From the tools and means you will need:

• open-end wrench to "30";
• ring wrench or head on "13";
• ohmmeter or autotester;
• liquid thermometer with a measurement range of up to 100 °C;
• clean container for collecting refrigerant;
• a container with water;
• gas (electric) stove or household boiler;
• dry clean cloth.

The check and replace algorithm is as follows:

1. We substitute the container under the plug on the cylinder block of the power plant.
2. We unscrew the plug, drain the refrigerant.
3. Disconnect the connector from the sensor contacts.
4. Using the key to "30" unscrew the sensor.
5. We connect the ohmmeter probes to the sensor contacts. The resistance between them in a serviceable device should tend to infinity. This means that the contacts are open.
6. We place the sensor with the threaded part in a container with water. We do not turn off the probes of the device. We heat water in a container using a stove or boiler.
7. We observe the readings of the thermometer. When the water reaches a temperature of 85–95 °C, the sensor contacts should close, and the ohmmeter should show zero resistance. If this does not happen, we change the sensor by screwing a new device in place of the old one.

Video: how to prevent the engine from overheating with a faulty sensor

injection engine

The injector "seven" has two temperature sensors. One of them works in tandem with a device that shows the temperature of the refrigerant to the driver, the other - with the computer. We need a second sensor. As already mentioned, it is installed on the pipe next to the thermostat. To check and replace it, we need:

• autotester or multimeter with the ability to measure voltage and resistance;
• open-end or box wrench to "19";
• liquid thermometer with temperature measurement amplitude up to 100 °C;
• heat-resistant container with water;
• boiler or stove (for heating a container of water);
• clean dry cloth.

The order of work is as follows:

1. We find the sensor. Disconnect the connector from its contacts.
2. We turn on the ignition.
3. We turn on the multimeter or tester in the voltage measurement mode. We connect the probes of the device to the connector contacts. Let's look at the evidence. The device should show approximately 12 V (battery voltage). If there is no voltage, the problem must be sought in the power supply circuit of the device.
4. If the device shows a nominal voltage, turn off the ignition and remove the terminal from the battery.
5. Using the key on "19", we unscrew the sensor. This may result in a small amount of coolant escaping. Wipe spills with a dry cloth.
6. We switch our device to the resistance measurement mode. We connect its probes to the sensor contacts.
7. We place the sensor with the working part in a container with water.
8. We heat the water, observing the change in temperature and resistance. If the readings of both devices do not correspond to those given below, we replace the sensor.

Table: dependence of the resistance value DTOZH VAZ 2107 on temperature

Forced fan on

Some owners of the "classics", including the VAZ 2107, install a forced fan button in their cars. It allows you to start the electric motor of the device regardless of the temperature of the refrigerant. Given the fact that the design of the "seven" cooling system is far from ideal, this option can someday help out a lot. It will also come in handy for those drivers who often move along country roads or are forced to stand in traffic jams.

Forced turning on of the fan is appropriate only on carbureted cars. In machines with injection engines, it is better to rely on the electronic control unit and not make any changes to its operation.

Video: forced fan on

The easiest way to make the fan turn on at the request of the driver is to bring two wires from the temperature sensor contacts into the passenger compartment and connect them to a regular two-position button. To implement this idea, you only need wires, a button and electrical tape or heat shrink insulation.

If you want to “unload” the button from unnecessary loads, you can install a relay in the circuit according to the diagram below.

In principle, there is nothing complicated either in the design of the fan itself or in its connection circuit. So in the event of any breakdown, you can safely proceed to self-repair.

The cooling system is designed in such a way that the fan starts only after the engine has warmed up to the set temperature. A failed fan switch can cause serious engine problems.

Do not confuse this sensor with the engine coolant temperature (CTO) sensor, which displays engine temperature on the instrument panel and is installed on the right side of the engine.

You can only notice its breakdown in time, perhaps only in the summer, and even then in the city or when driving slowly, since the oncoming air flow is quite enough for the normal operation of the cooling system. The cooling system fan, on VAZ 2107 cars, starts with a characteristic noise, so the moment it starts is clearly audible.

Where is the turn-on temperature

The fan activation sensor is located for injection models, on the aluminum outlet pipe of the cylinder head (article - 23.3828, used in VAZ-2107i-2112, 21213, 2123, ALFA ROMEO, DAEWOO, FIAT, LANCIA, OPEL), on carburetor models (TM 108 -02 92/87 C) it is installed on the engine cooling radiator.

For the “classics”, the fan operation temperature is 92 degrees and the shutdown temperature is 87 C 0, therefore, installation of a suitable size, but with a different number, is not recommended.

On carbureted models, the sensor is located on the radiator

Checking the electric fan and its circuits

In order to check the operation of the fan and power circuits on the injector "seven", you need to disconnect the connector from the sensor, the ECU will give the command to turn on the fan. If this does not happen, then it is not the sensor itself that needs to be checked, but the health of the F7 fuse, the electric motor, the fan relay and the power circuits. Below is a diagram for switching on the cooling fan VAZ 2107 injector.

Scheme of switching on the cooling fan VAZ 2107 (injector)

The principle of operation of such a device differs from TM 108 and is based on a change in resistance.

When the sensor heats up, it reduces the resistance, the ECU controls this change and, when the set parameter is reached (about 195 ohms), turns on the fan relay.

On the carburetor model, everything is made somewhat simpler, if the fuse and relay are working, then in order for the electric motor to work, it is enough to remove the chips from the sensor and close them together.

The principle of operation of the fan switch-on sensor installed on the radiator is such that when cold, the bimetallic plate opens the contacts, and when the temperature reaches 92 degrees (ideally), it closes and the relay is activated. In practice, quite often you can buy sensors with a certain spread of values. You can check the new one by heating it in water, controlling the temperature and turning it on.

Diagnostics

You can check the fan on sensor by measuring the resistance under various temperature conditions. To do this, use a tester (multimeter) in ohmmeter mode and measure the resistance of the part. It should decrease in proportion to the heating of the coolant, as already mentioned, the higher the heating, the lower the resistance.

The resistance can be checked without removing it from the machine, for this it is enough to remove the chip and take measurements on the contacts of the part and warm up the engine by controlling its heating using the instrument on the panel. See below for a table with approximate values ​​for the dependence of resistance on temperature.

Before installing a new controller, you can check the change in resistance in a container of heated water.

You can check the electric motor by applying voltage from the battery, the blue wire is “+”, blue with black or just black is “-“.

It happens that the fan starts at unusually high temperature values, this indicates a malfunction.

If during the test it turns out that the electric motor, fuse, sensor are all OK, in this case, you need to check the health of the relay. Sometimes the contacts just burn out. In the photo below

The fan relay on the VAZ 2107 injector is located on an additional block under the "glove compartment" (see photo), it is the far left number 23-3787.

VAZ 2107 fan relay (injector)

If you have nothing to replace this relay, then you can fix it. The contact is attached to the plate and in order to restore its performance, it is enough to press the contact. For this:

It should be noted that over time, the breakdown is repeated, checked.

Sensor replacement

Replacing the sensor on an injection model is easier than on a carburetor model, since there is no need to drain the coolant. It is enough to put some kind of rag to absorb the spilled coolant. With a key of 19, the part is unscrewed, a new one is removed and quickly installed. When installing, it is rational to apply sealant to the threads in advance.

To carry out the replacement procedure on a carburetor machine, you must first drain the antifreeze (antifreeze) and only then unscrew the sensor with a 30 wrench and install a new one.

When buying sensors and temperature controllers, try to choose branded parts.