The standard fan switch-on sensor is designed to start the relay during the period when temperature regime liquid intended for cooling a running motor reaches certain values, above which the engine will overheat.
Often, novice motorists ask the question, where is the sensor for turning on the fan of a VAZ 2110 car, and others cars. We inform you that such a device is located on the car radiator. This device cannot be repaired and replacing the fan on sensor when it fails is the only solution.
On the "top ten", however, as on many other cars with liquid-cooled power plant to stabilize the level operating temperature motor, an electrically driven climatic fan unit is used. Entering the fan into operation, as well as removing it from this position, takes place automatically, and the fan switch-on sensor serves as a signaling device in case of emergency excess of temperature values.
The sensor for turning on the cooling fan in carbureted cars
If the “ten” is equipped with a carburetor-type motor, then to perform the function of warning about overheating of the power plant, a sensor for turning on the cooling fan TM-108 of a thermobimetallic type is used, while in the VAZ 2110 injectors these functions are assigned to the controller.
If the fan unit is “commanded” by the fan switch-on sensor, then its initiation is directly related to the temperature setting of this device. This information can be obtained by reading the inscriptions on the body of the product.
Upon reaching the critical temperature values, the fan switch-on sensor must initiate the operation of the fan unit. If this does not happen, you should look not only for where the fan switch-on sensor is located, but also for a malfunction of this control device.
The test for the functionality of the device is quite simple - it is only necessary to close the contacts of the device and, if the fan installation works when it is started, then it is necessary to replace the fan switch-on sensor with a working element.
If during this test the fan unit does not turn on, then it is required to check the suitability of the fuse for further use and the serviceability of the supply wiring.
Operation of the cooling fan in injection cars
The operation of the fan unit for cooling the temperature in injection motors is assigned to the electronic type motor controller. His software set to trigger the engine overheating protection system in the temperature range from 100 to 105 degrees Celsius. In the event of a defect in the operation of the VAZ fan switch-on sensor with an injector, the controller “remembers” the error code and when the motor is on, the fan starts to work.
However, there are separate precedents when the electronics in the form of a controller cannot “read” a defect and the fan installation may not start functioning when extreme temperatures are reached, i.e. above 105 degrees Celsius. Then, to test the circuit and the device, it is required to disconnect the contact of the cooling fan switch-on sensor when the motor is on.
If the circuit is functioning, then the fan installation should turn on and turn off when reversed. If the circuit does not function, then a suitability test should be carried out. safety device and technical readiness of wiring and relays.
A quick check of the system is carried out as follows: we bridge two contacts of the relay of the fan installation. If the product works in this position, then, without disconnecting the relay from the wire block, bridge the body of the relay and its contact using the “control”. In this position, the relay should function like a fan unit, which means that the controller or the connecting wire of the relay with the contact of this device is faulty.
If there is no sound of relay initiation, there is only one conclusion - the part needs to be replaced. If the fan unit does not start working when the relay outputs are closed, it is necessary to test the fuse for integrity and power supply to the terminals of the fan unit. If power is supplied to one contact and is absent on the other, then this may indicate defects in the EDH of the fan installation.
Replacing the fan on sensor on the "top ten"
Timely replacement of the VAZ 2110 fan switch-on sensor is carried out using an ordinary set of locksmith tools.
Replacement order:
- Drain the coolant from the radiator and de-energize the fan switch sensor.
- Remove the device from the radiator housing.
- Install a new device with a copper sealing ring.
Before installing the product, it is necessary to connect the terminals of the megohmmeter to the terminals of the output contact on the VAZ fan switch-on sensor. This is how the functionality of the product is tested.
You can control the inclusion of a working product by means of heated water, where the sensor should be placed. In this case, the contact terminals of the device should be closed. At a temperature of about 95 degrees Celsius, the megohmmeter should show the resistance of the product, which will indicate that the product is in good condition.
The car engine converts only part of the fuel combustion energy into useful work. A significant percentage is spent on heating the body of the unit, which needs to be cooled. The reliability of the functioning of the cooling system directly depends on the health of the wiring and the fan switch-on sensor.
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Fan On Sensor Functions
The fan activation sensor is designed to perform the following functions:
- activation of the fan impeller when a certain temperature is reached;
- fan speed adjustment during cooling (not on all vehicles);
- turning off the fan, which protects the power unit from hypothermia.
Where is the sensor located and how does it work?
Fan activation sensors are located on the elements of the cooling system. The installation point is located in the path of the fluid flow supplied from the engine jacket to the radiator. This is due to the fact that the liquid in this line will have the highest temperature.
VAZ car sensor installed at the bottom of the radiator
Possible installation locations:
- thermostat housing outside the valve;
- cylinders;
- lower radiator hose;
- side of the radiator.
On some vehicles, the sensor is combined with a coolant thermometer. The fans are switched on by the control unit according to the temperature data. At the same time, there is an additional sensor on the radiator used for climate control or air conditioning. The operation of any of the devices turns on both fans (on the radiators of the engine and air conditioner). A similar solution is found on Japanese cars.
On cars, two fan activation sensors can be used, located at the inlet and outlet of the pipes from the radiator. Such a scheme allows you to maintain the temperature in a narrow range.
Varieties
On cars, the following types of sensors are used to turn on the fan:
- bimetallic;
- wax;
- thermistor;
- a sensor that works to break or close the circuit.
The first two types of sensors have an electromechanical scheme of operation and can be of two varieties:
- single-speed, equipped with a single contact group that controls the fan in one temperature range;
- two-speed, equipped with a pair of contact groups configured to work at different temperature ranges.
Regardless of the type, the sensors are a metal case equipped with a thread. Non-ferrous metals based on copper (bronze or brass) are used as the body material, providing increased thermal conductivity. On the body there is a turnkey hexagon that serves to install the part. The wiring connector is located on the top of the sensor.
Bimetal sensor
A metal plate is installed in the bimetallic sensor. In the normal state, the contacts are open. As it heats up, the plate deforms and closes the circuit, giving a control signal to the relay for turning on the impeller electric motor. There are sensors that activate the fan motor directly without a relay. When the liquid cools, the plate returns to its original shape, and the current supply to the motor stops.
The principle of operation of the sensor on a carburetor engine Wax gauge
Sensors were produced for which wax or ceresite (or another substance with a significant coefficient of thermal expansion) was used as a working substance. As it warmed up, it expanded and shifted the metal membrane associated with the contacts. As the wax cooled, the volume of the wax decreased, and under the action of the spring, the contacts opened.
Wax sensor Thermistor sensor
The thermistor sensor works on the principle of changing the resistance of a resistor installed in a fluid flow. The change in temperature is recorded by the electronic unit, which recalculates the temperature value in accordance with the schedule.
Sensors working for breaking or closing the circuit
Devices that turn on the fan when the circuit is broken are often found on Japanese-made cars. The sensor type can be checked by removing the plug. When dismantling the block from the sensor, working on a break, the fan will turn on.
At what temperature is the fan switch activated?
The temperature range of the sensor response depends on the type of motor power supply. On carburetor machines, devices with a switching range of 82-110 ºС are used. The activation temperature is stamped on the body of the part. On cars of the same model, there may be sensors calibrated for different temperatures.
According to the standard, the sensors are divided into four groups according to the operating temperature:
- 82-87 ºС;
- 87-92 ºС;
- 92-99 ºС;
- 104-110 ºС.
On Russian cars, sensors of the first three groups are used. The engines of foreign cars are designed for a more severe temperature regime, so they often have devices of the fourth category.
With the beginning of the use of multiport injection systems, the fan switch-on temperature is determined by the setting of the engine control unit. The sensor simply transmits information about the temperature to the control unit, which makes a decision to turn on the fan according to the programmed program.
On injection machines, you can program the temperature thresholds at which the fan switch-on sensor will work. This should be done carefully, as it is easy to violate the temperature regime and damage the engine.
How to check the fan switch sensor?
The inclusion sensor can be checked without removing it from the car, or dismantled. Checking the device that has not been removed allows you to check the health of the device, and the response temperature range can only be checked by dismantling the product from the car.
Checking the removed sensor:
- Prepare a container, thermometer and multimeter. The multimeter is set to ohmmeter mode.
- Place the sensor in water, heat it to the required temperature. At a low temperature, the resistance of the sensor is shown as infinite.
- Wait for the moment of a sharp decrease in resistance. Check the switch-on temperature of the sensor.
- Gradually cooling the water, determine the contact opening temperature.
- Compare the obtained data with passport values.
In the absence of a tester, the fan switch-on sensor can be checked with a control lamp that lights up when the contact group is activated.
Dmitry Maznitsin, the author of the video, shares the secrets of checking the fan sensor.
In a car with a carburetor engine
Check sequence with carburetor:
- Switch off the ignition.
- Carefully remove the wires from the sensor. When dismantling, keep hands and clothes away from the fan impeller, since the electric motor can be started even with the ignition off.
- Connect the wires in the plug.
- Turn on the ignition. The fan should start running. If the mechanism does not start to rotate, then the problem lies in the electric motor or wiring.
It is allowed to operate the car engine with closed contacts of the wiring coming from the sensor. The connected cables must be insulated against a short circuit to the vehicle body.
In a car with an injection engine
The procedure for checking the sensor on an injection car:
- Remove the connector from the sensor.
- Turn on the ignition. The Check Engine light on the instrument cluster may come on, indicating an error in the cooling system.
- Start the engine. After a while, the motor control unit will go into emergency mode and forcibly start the fan for continuous operation.
- After arriving at the car service, it is required to diagnose the car and delete the errors recorded in the control units.
If the fan does not turn on in emergency mode, then the problem lies in the impeller drive or wiring. The car is delivered to the service using a tug or tow truck.
How to replace the fan switch sensor?
Typical set of tools and accessories for replacement:
- set of heads;
- ratchet extension;
- pliers;
- screwdriver with a flat sting;
- sealant;
- head for removing the sensor or a suitable wrench;
- capacity for draining the liquid (for 5-6 l);
- coolant for topping up (0.4-0.5 l).
The sequence of steps for replacement:
- Cool the engine to a comfortable temperature.
- Place a container and drain the coolant from the radiator. You may need to remove the crankcase guard or plastic splash guards to access the drain cock. On some vehicles, the heating pipe must be removed.
- Disconnect the wiring plug from the sensor. Inspect the terminals, clean from dirt and traces of oxidation. Check the condition of the wires suitable for the plug. In case of cracking or other defects in the insulation, it is necessary to replace the worn section. Connection of new wires must be carried out with respect to polarity.
- Unscrew the faulty sensor. Applying a lot of force is not recommended, as there is a risk of damage to the radiator. To facilitate the process, the use of liquids such as WD40 is allowed. It may be necessary to remove the battery, the platform under it, or the engine air ducts to access the sensor installation site.
- Lubricate the threads of the new sensor with a high temperature sealant.
- Install a new O-ring on the sensor. Reuse of gaskets is not recommended because the joint is not sealed.
- Screw the sensor into place and tighten to the required torque.
- Install the wiring plug on the sensor.
- Restore the coolant level in accordance with the vehicle service manual.
- Warm up the engine to operating temperature and check the operation of the new device. During the first days of operation, carefully monitor the temperature of the coolant. This applies mainly to domestically produced cars, since the sensors are often defective or set to the wrong response temperature.
On some vehicles, after the ignition is switched on, a diagnosis of a new sensor is carried out, which consists in turning on the cooling fan for 15-20 seconds (on a cold engine).
How to choose a new sensor?
- the operating voltage of the sensor must correspond to the voltage in the on-board network;
- the connection plug must match the wiring harness;
- the sensor must match the current in the circuit. It is unacceptable to use a device designed to work with a relay in the fan direct connection circuit;
- the temperature response range should be close to the marking on the broken device;
- the sensor housing must be threaded and the length of the threaded part of the appropriate size.
On modern foreign-made cars, the fan switch-on sensor is selected according to the original spare parts catalogs.
How much does a sensor cost?
The cost of the sensor depends on its type and brand of car.
The cost of sensors for some types Vehicle can reach up to 3-6 thousand rubles.
The radiator cooling fan is one of the key elements that save the motor from possible overheating. It should turn on when the coolant is too hot and not cool enough as it passes through the radiator. For example, this situation occurs when the engine is running on Idling or driving at low speed, especially when the ambient temperature is high.
The sensor is responsible for turning on / off the cooling fan. It should work when high temperatures by activating the fan. If it doesn't, the sensor will need to be replaced. In this article, we will look at how to determine that the radiator cooling fan sensor has failed.
How does the radiator cooling fan sensor work
To understand how to check the sensor, you must first understand its principle of operation. The radiator cooling fan sensor is arranged very simply, but it is somewhat different on carburetor and injection engines.
In the carburetor, it has two contacts and a bimetallic plate. When the bimetallic plate is heated to a temperature determined during the production of the sensor, the contacts close, and current begins to flow through them to the fan, turning it on. On the injector, the sensor activation system is almost the same, except that the engine control unit sends the turn-on command, analyzing the need to activate the fan based on information from several other sensors.
Sensors on carburetor engines are triggered when a certain temperature is reached, and the driver can look at the markings on the body of the device to determine in which temperature range the sensor will work. Usually, such sensors are activated at a temperature of 92 to 97 degrees Celsius. If the driver is worried about the possible overheating of the engine, he can find a sensor on sale that works at a lower temperature and install it. On injection engines, the sensor response temperature is flashed into the "brains" of the vehicle control unit.
Where is the radiator cooling fan sensor located?
Manufacturers determine the location for installing the fan activation sensor, depending on the design features of the engine. Most often it is placed at the bottom of the radiator, but sometimes it is more expedient to place the sensor near the thermostat and cylinder block.
How to check the radiator cooling fan sensor
We recommend reading:The methods for diagnosing the sensors in question will differ, depending on which motor they are installed on and how they are turned on:
The options with a complete failure of the sensor are considered above. In this case, situations are possible when it fails partially, for example, it works at the wrong temperature. This can also be checked in the following way:
Depending on the results obtained, a decision can be made about the serviceability or malfunction of the sensor. If it worked at a temperature below the declared temperature, then such a sensor has some problems, but it can prevent the engine from overheating by turning on the fan in advance. It is much more dangerous if the sensor is triggered at a temperature higher than the declared one, in which case it will need to be replaced.
Automotive fan-driven cooling systems provide automatic switch on and turning off the fan when the coolant temperature changes. The main role in the system is played by the fan switch-on sensor - you can learn everything about this component from this article.
What is a fan switch?
- an electronic or electromechanical device with a contact group (groups) that closes or opens electrical circuit depending on temperature. The sensor is included in the power supply or drive control circuit electric fan engine cooling system, it is a sensitive element that sends a signal to turn on or turn off the fan, depending on the temperature of the coolant (coolant).
These sensors are only used in vehicles equipped with electrically driven radiator cooling fans. The turning on and off of the fans driven by the engine crankshaft is carried out using a viscous coupling or other means that are not considered here.
Types of fan switch sensors
All fan switch sensors are divided into two groups according to the principle of operation:
Electromechanical;
. Electronic.
In turn, electromechanical sensors are divided into two types:
With a sensitive element based on a working fluid with a high coefficient of expansion (wax);
. With a sensitive element based on a bimetallic plate.
Thanks to design features electromechanical sensors can be connected directly to the fan power circuit (although more often the sensor is connected to the fan relay circuit), and electronic sensors can only be connected to the fan drive control circuit.
Also, electromechanical sensors are divided into two types according to the number of contact groups:
Single-speed - have one contact group, which closes in a certain temperature range;
. Two-speed - have two contact groups that close when different temperatures, which allows you to change the fan speed depending on the coolant temperature.
In this case, the contact groups can be in one of two states: normally open and normally closed. In the first case, the fan turns on when the contacts close, in the second case, when they open (additional control circuits can be used here).
It is a fan switch-on sensor, a temperature-sensitive element enclosed in a copper alloy housing. This metal is used due to the fact that it is able to conduct heat well, and also cools down quite quickly. The sensor is installed in the lower or upper part of the radiator of the cooling system. It depends on the make and model of the car, or more precisely, on the type of sensor used.
Fan sensor functions
It is difficult to overestimate the useful properties of the electric fan switch-on sensor. It automates the operation of the cooling system, allows you to turn on additional airflow without the participation of the driver. To do this, a temperature-sensitive element is installed in the housing, which reacts to changes in the temperature of the liquid in the system. In fact, the sensor is a switch with normally open contacts.
Can be compared with circuit breakers, which are commonly used for electrical installation work in homes and businesses. Their base is a bimetallic plate that deforms when heated. The situation is similar in the fan activation sensors: the plate bends under the influence of temperature. When she reaches certain value, the contacts are closed, applying voltage to the power supply circuit of the fan motor.
Switching scheme option without relay
Sensors on some vehicles, for example, the VAZ 2108-21099 fan switch-on sensor, since the mid-90s, are able to withstand high switching currents. The contacts of the switch installed in the housing do not burn, the presence of a spark gap does not harm them. Therefore, in order to save and simplify, a relayless type switching circuit is used.
The power supply circuit of the electric fan is connected to the positive terminal of the battery permanently. All work is controlled by connecting the negative wire. There is a wire from the "+" battery to the fuse box. Then it passes through a protection device (fuse) and immediately, without unnecessary switching devices, is connected to the positive terminal (red) of the fan. The negative wire of the electric fan (black) is connected through the switch-on sensor to the car body.
Switching circuit using a relay
The use of a relay makes it possible to protect the sensor contacts from high switching currents, since it is used only to close the low-current power supply circuit of the electromagnetic relay winding. The essence is practically the same as in the previous scheme, but one element is introduced - a relay with normally open contacts. It is better to power its coil not from the ignition switch, but directly from the battery, so that in case of severe overheating, even with the ignition off, airflow occurs and the temperature drops to the optimum value.
If you decide to change the switching scheme, then you need to use black and red wires, a relay and a connector for it, and a heat shrink tube. First of all, you need to find appropriate place to install an electromagnetic relay. Access to it must be free, and the wires must not touch the engine and moving parts. From the sensor, connect the wires to the contact group of the relay. Connect one output from the coil to the body through the cooling fan switch-on sensor, and connect the second to the positive terminal. Installation is completed, all wires must be insulated and tightened with plastic clamps.
How to check the sensor?
Before you check the fan switch on sensor, you need to know how it works. In a nutshell, then the two outputs of the device, when heated above the value indicated on the case, are closed. Based on this, it can be said that the most the right way checks are heating of a sensitive part of the case. To do this, you will need to remove the sensor from the radiator, clean it from dust and dirt, and, if necessary, tidy the conclusions.
Use a tester to check. You can use both the most primitive, made from an incandescent lamp and a battery, and a more advanced one - a multimeter in the continuity mode. Please note that open flame heating is prohibited. Boil water in a small container, connect the tester to the sensor contacts, dip the sensitive side of the element into boiling water. The contacts should close, you will see this: the lamp will light up or the multimeter will beep. And if the tester shows that the contacts are closed before you lower the sensor into the water, then you can not carry out further testing: it is clearly faulty.
Carrying out a replacement
On almost all vehicles, the replacement of the fan switch-on sensor is carried out according to the same scheme. True, in some it is necessary to drain all the liquid from the cooling system, while in others it is enough only from expansion tank. The first ones are those in which the sensor is located at the bottom of the radiator, the second - at the top. If you need to drain all the liquid, then do not forget that the stove tap must be opened so that the liquid does not remain in the lower part of the system. For convenience, you can install the car so that its front is higher than the rear (uphill).
When you get rid of the liquid, you can begin to dismantle the old sensor. Remove the wires connected to it. Then, using a suitable wrench, rip the case out of place. Then you can unscrew it by hand. Tighten the new sensor first by hand, at the end, make a final tightening with a wrench. Thread tape can be used to avoid leaks. It is able to seal the connection, the liquid will not leave. Then install the wires and pour antifreeze into the system.
Turning on the fan with a button
On any car, the sensor can fail. Well, if this happens at a time when the engine is not under load. But if a breakdown caught you in a traffic jam, then the temperature of the liquid in the system will begin to rise slowly, as a result, the boiling process will begin. In such cases, there is nothing left but to open the stove radiator completely (this is especially "nice" in the heat) or to connect the fan leads to the battery.
For safety, it is best to install an additional button in the cabin, when turned on, the electric fan will start. You only need to run two wires from where the fan switch sensor is located to where the button is supposed to be installed. If you have a switching circuit using a relay, then the solution to the problem comes down to connecting two wires on one side to the sensor outputs, and on the other to the switch contacts. If the relay is not installed, then it is better to re-equip the circuit and install it. It is not necessary to switch large currents with a button.
Two fan speeds: implementation
A step change in the speed of rotation of the electric fan rotor is used on some vehicles. You can do this on any machine that does not have forced airflow installed. You will need two sensors. Only the response temperature difference should be a few degrees. For example, at 92 degrees, the fan should rotate slowly, and at 100, it should turn on and work on full power. But when implementing such a solution, pay attention to the fact that the temperature is minimal in the lower part of the radiator.
If there is a radiator fan switch-on sensor with a response temperature of 95 degrees below, then during the upgrade you can supplement the system by mounting the same device next to it, but its response temperature should be 5 degrees lower. In order not to drill holes in the radiator, you can mount it in a rubber pipe. The control scheme is almost the same as with the relay. But by using a resistor (for example, as in the power supply circuit of a stove fan), it is possible to reduce the rotational speed of the electric fan rotor.
Conclusion
There are not so many options for upgrading the inclusion of a fan, but when operating a car, there is a need for emergency mode. Therefore, installing a button in the cabin is useful, not only in old cars, but also in modern ones. When working on electrical equipment, turn off battery. The speed of rotation of the fan impeller is high, so it is better to play it safe by placing a piece between the blades wooden block to prevent accidental starting of the motor.
