Connecting the fan activation sensor. Fan activation sensor: principle of operation and malfunctions. How to choose a new sensor

The fan on sensor is a special device that activates the fan located at the bottom of the radiator. This happens if the temperature of the antifreeze () rises and the engine overheats.

[ Hide ]

Description of the fan switch sensor

DTOZH and the fan on sensor are two different regulators. DTOZH gives the ECU temperature readings, and the ECU turns on the fan itself. The second regulator, as a rule, is a power one, closes the contacts at a certain temperature - turns on the fan relay and is located mainly on the radiator, since the DTOZH is located on the engine.

In more detail about how the fan sensor is arranged, what functions it has, how to diagnose this device - just below.

Purpose and functions

The radiator fan activation sensor improves cooling system performance, including auxiliary airflow, without driver intervention. To perform these manipulations, a special element is installed in the device case, which reacts to changes in the temperature of the liquid.

In plain language, we can conclude that the determinant that turns on the cooling fan is a real switch. It is activated when the temperature rises for a long time, when the plate bends, and then the contacts close, supplying current to the fan power circuit.

Principle of operation and location

It, as mentioned, is located at the bottom of the radiator and turns on when the temperature reaches a certain point.

It happens like this:

1. The plate, which is located at the bottom of the device, begins to change as the temperature rises.
2. Bending, it puts pressure on a special piston, which moves forward and closes contacts during movement: both movable and stationary.
3. If the antifreeze stays cold, the plate won't heat up and eventually the contacts won't close, causing the fan to turn on.

Each machine is individual and its temperature too, so there are no specific indicators at which the device is triggered. The difference is also present in the speed of rotation: there are two-speed and one-speed. The two-speed switching option is rarer, but it also occurs. It differs in that when the peak temperature is reached, a pair of contacts closes, and the fan spins at low speeds.

It can often come out of a malfunction in a car of domestic origin. If this happens, if you notice that a malfunction has occurred in the system, you must immediately drive the car into the garage and change the device. You can also find out where the fan switch sensor is located from the video from the author of Avto-Blogger.ru.

How to check the sensor yourself?

Checking the fan switch on sensor is a simple matter.

1. If there is a need to diagnose it, you must first find out its functions and principle of operation.
2. After that, you can check the system by heating the most vulnerable part of the sensor housing. To do this, you need to remove it from the radiator, carefully inspect it, check the contact pads, inspect the wires, and, if necessary, clean it.
3. Next, you need a tool that you can make yourself from an ordinary light bulb and a battery, or use a special tester.
4. Bring water to a boil, then connect the tester and sensor contacts and lower its vulnerable side into the water.
5. After that, a closure should occur. This action will cause the lamp to ignite, or the characteristic sound signal of the tester to appear. If the device showed that the contacts closed before colliding with boiling water, then the sensor is undoubtedly faulty. How to check the fan switch-on sensor, the author of the video, the Mechanical Technician, will tell.

Instructions for replacing the regulator

Replacing the fan on sensor almost always occurs according to the same scheme:

1. The ground needs to be prepared. In some cars, this happens as follows: you need to rid the system of cooling liquid if the fan is installed at the bottom of the radiator, or, if the system is enough, remove water from the expansion tank. If the antifreeze needs to be completely drained, then it is necessary to open the stove tap so that there is no residue. Important: do not pour the rest of the liquid on the ground, because antifreeze is quite poisonous.
2. After that, you can remove the sensor by disconnecting the connected wires. Then, using the key, you need to remove the case and unscrew it with your hands. The new fixture must be screwed in by hand, then a wrench can be used for finishing touches. To prevent leakage, you can use a special thread tape, which will make the connection tighter and more reliable. After that, you can restore the contacts by returning all the necessary wires to their place, and pour coolant into the system.

Issue price

In the photos below you can see what the device looks like, as well as estimate the cost of various models.

The request returned an empty result.

Video "Replacing DTOZH"

Overheating of the engine threatens with serious consequences: the piston will jam, it will break through, which will turn into a major overhaul of the power unit. Therefore, the cooling fan is an important element that protects the power unit from extreme heating.

We change the fuse

Video on replacing the fan switch sensor

Checking the operation of the cooling fan motor

The easiest way to check the operation of the fan is to throw two straight wires on it: minus and plus.

Plus is taken from the battery, minus from the car body. If it does not work when the circuit is closed, then the problem lies precisely in it. When starting the blades, we are looking for a problem elsewhere.

The scheme of the cooling fan

Basically, when a non-working fan is detected, several reasons are identified:

• The electric motor burned out, a break in the winding;
• Wear of carbon brushes;
• Seized or broken bearing.

If in the last two cases the problem is solved, so to speak, with little bloodshed, the first one involves replacing the electric motor.

Important! When wiring, the main power supply of the electric motor must be disconnected.

Procedure for verification

The operation of the fan on the VAZ-2114 is tied through 2 fuses. One of them is also responsible for the sound signal. You can check it by clicking on the horn. If there is no sound, replace with a whole one. It is located in the mounting block, it is 20 amp, marked F5.

Check and, if necessary, change the fuses

The second one is under the dash, on the passenger side. Under the casing there are 3 relays with a fuse for each. The middle pair is responsible for the operation of the cooling fan. Replace the blown element with a new one (the fuse can be “ringed” with a multimeter or limited to visual inspection. An ohmmeter is required to check the relay’s performance). Checking their condition, at the same time make sure that the contacts are in a good condition, clean them if oxide is found.

Important! Having found a blown fuse, you should not be limited to replacing it with a new one. It is imperative to find the cause of the break, as in the near future the new one will burn out again.

Checking the fan on sensor

If no cause is found, The next step should be to check the operation of the fan switch sensor. It is not difficult to do this. Disconnect it and turn on the ignition, while paying attention to the fan. The rotation of the blades indicates that the cause of the problem is in the sensor.

Checking the cooling fan switch

In view of the fact that it is very often the sensor starts to fail, giving erroneous signals, it is recommended to check it in one more way. To do this, you need a container with, a thermometer and a multimeter. Wires from the measuring device are connected to the sensor terminals, the threaded part of the sensor is immersed in the liquid. Heat the contents of the container to the temperature of the fan operation (on the VAZ 2114 - 92 degrees). When the contacts are closed, the multimeter will beep. So the sensor is working, if this does not happen, you can safely throw it away and buy a new one.

Healthy! Before installation, it is advisable to check the performance of the purchased sensor in the same way.

Video about checking the sensor for turning on the cooling fan

Final check

After fixing the problem, start the engine of the car. The fan motor should start after about 5 minutes of idling. If this does not happen, and the temperature has reached the desired norm, carry out troubleshooting again.

Video about the reasons why the cooling fan on the VAZ-2114 does not turn on

As you know, overheating the engine does not lead to absolutely anything good. To prevent this from happening, car manufacturers began to install radiator cooling fans, and often not even one.
This article contains detailed instructions for replacing the sensor for turning on the electric radiator cooling fan with your own hands. You can also watch a video that clearly shows the essence of the process in detail.

• General theoretical information

1. Where is the fan switch located?
2. At what temperatures should it work?
3. On what principle does it operate?

• Other causes of a non-working fan
• Checking the operation of the fan switch sensor
• Replacing the fan switch sensor

1. Instruments
2. Sensor replacement
3. Replacement without draining antifreeze

General theoretical information

Where is the fan switch located?

So:

• The answer to this question is very simple - in. In different cars, on different radiator designs, the sensor may be in the left tank or right, bottom or top, but it will always be in the radiator.
• It is very simple to determine it - this is the only thing in the radiator to which the electrical wires fit, and also in the radiator area there are few things that are unscrewed with a 30 key. So when the fan sensor is replaced on a VAZ 2107 or another VAZ, it is very difficult to make a mistake.

At what temperatures should it work?

• Sensors are available with different temperature limits.
• Often turns on at 92 degrees and turns off at 85-87 degrees.
• There are sensors with switching intervals from 92 to 98 and switching off from 82 to 87. When buying, choose the sensor that you had or the most common - 92/87.

On what principle does it operate?

In order to make the replacement of the fan switch-on sensor on the VAZ 2110, of course, it is not necessary to know this, but it will come in handy for general development:

• The sensor has a contact group.
• When the coolant inside is heated, the sensor contacts heat up and expand.
• Reaching a certain limit, the contacts close, a signal is transmitted to the wires and the fan is activated.

Other causes of a non-working fan

If your electric cooling fan has stopped turning on, do not rush to sin on the sensor. Before replacing the fan switch on sensor with a VAZ 2106 or another model is done, check the remaining points.
This is:

• Fan failure. One of the reasons may be the failure of the . The price of its replacement, of course, is more expensive than the sensor, but anything can happen.
• The operability of the fan cannot always be checked by closing the two contacts of the fan switch-on sensor. Because the chain can be broken.
• The most reliable way to check the performance of the fan is to connect its contacts directly to the battery using two long wires. If the fan does not work, then it should be changed.

Checking the operation of the fan switch sensor

You can check the new sensor before replacing, or you can check the old one after replacement to calm your conscience.
How to do it? Very simple - for this you need a multimeter, a thermometer, a container and water or coolant.
So:

• Pour water or into prepared container.
• Lower the threaded part of the cooling sensor there.
• Connect the terminals of the multimeter to the sensor contacts and set it to the resistance measurement mode, and if there is a continuity mode, then it is better to use it.
• Dip the thermometer into the liquid.
• Next, heat up the water.
• When the temperature of the liquid is reached, at which the sensor should turn on (usually 92 degrees), its contacts should close and the multimeter should beep.
• If this does not happen, the sensor is faulty and should be replaced.

Advice. Do not be surprised if you have purchased a faulty sensor. Just go to the dealer and change to a new one.

Replacing the fan switch sensor

This section covers the replacement of the VAZ 2107, 2110 and 2114 fan switch-on sensor. In principle, all these processes are the same on any car, the differences are only in the details.

Advice. Before replacing the sensor, read the instructions, view the photo.

Instruments

For this operation, a lot of things are not required:

• Key for 30 cap
• rags
• Coolant tank

As you can see, replacing the VAZ 2109 fan switch-on sensor by yourself will not cost much. You only need to buy a sensor.

Sensor replacement

Note! Sensor replacement is best done on a cold engine. So you can avoid getting burns on the skin of the hands and other parts of the body.

So:

• It is not necessary to drive the car onto a flyover or inspection hole - this will even cause some inconvenience. It will be enough just a closed room - a garage.
• Disconnect the negative terminal from the battery.
• First you need to drain the antifreeze from the radiator. There is no need to drain it from the cylinder block.
• Unscrew the plug of the expansion tank of the engine cooling system.
• To drain the antifreeze, it is necessary to unscrew the drain plug of the radiator. It is usually located at the bottom of the radiator and is simply unscrewed by hand.

• Place a container for antifreeze under the car and wait until it drains completely.

Advice! Use a clean container, as the same antifreeze will have to be poured back.

• Screw the drain plug back in.
• Disconnect the contacts from the sensor.
• With a key of 30, unscrew the fan switch on sensor.
• Unscrew carefully so as not to damage the plastic tank of the radiator.
• Screw the new sensor in place of the old one. Don't forget to install the copper gasket under the new sensor.
• Reconnect the wiring to the sensor.
• Pour the antifreeze that was previously drained into the expansion tank.
• Blow out the cooling system so that there is no air in the system.
• Connect the battery terminal.
• Start the engine, warm it up and check the sensor for proper operation.
• If the fan turns on at the right temperature, then everything is in order.
• If not, then you will have to check the other possible malfunctions of turning on the fan.

Replacement without draining antifreeze

Replacing the fan sensor on a VAZ 2110 with draining antifreeze takes a lot of time. Of course, not as much as an engine bulkhead, but still, if you omit the drain and fill of antifreeze from the process, you can save a little time.

Advice! For such a replacement of the sensor, a certain skill and at least some experience in car repair is required.

• To quickly replace the sensor, rip off the old one with a 30 wrench and unscrew it almost completely.
• Next, you need to prepare a new sensor so that you unscrew the old sensor with one hand, and quickly screw in the new one with the other hand.
• Thus, the loss of antifreeze will be small.
• After such a replacement, wipe the place around the fan switch-on sensor with a rag to determine the presence or absence of an antifreeze leak.

In this way, you can carry out this operation a little faster.
Do not be afraid to repair your favorite car with your own hands. Despite the fact that the price of auto repair is not small now, it is very profitable. In addition, experience in life is always useful.

An internal combustion engine has a narrow operating temperature range. Exceeding it leads to serious consequences, up to the failure of the power plant. To prevent the occurrence of overheating of the motor, its temperature is monitored by the fan switch-on sensor and the brains of the injector.

The principle of operation and temperature characteristics of the device

The principle of operation of the sensor for turning on the engine cooling radiator fan is based on the difference in the linear expansion of metals. When the coolant is heated, the bimetallic plate of the device changes its position. At a certain moment, the contact group closes. A signal is transmitted to turn on the fan. In some sensors, when the engine overheats, an open circuit occurs.

Depending on the model, the sensors have a variety of temperature response limits. So, to turn on the VAZ 2114-2115 fan, a temperature of 102-105 ° C is required. The shutdown signal comes when the engine temperature drops to 85-87°C. When choosing a new sensor for your car, the car owner must focus on the old device. In the absence of the original, previous device, the necessary information can be obtained from special catalogs.

Most modern fan control systems do not have sensor limits. It does not operate in relay mode, but constantly transmits information about the engine temperature to the electronic control unit. The ECU itself has limits for turning the fan on and off. Changing the operating range will require reprogramming of the brain.

Wiring diagram for the fan on sensor in injection engines

Unlike carburetor cars, where the sensor directly closes and opens the cooling fan circuit, in injection engines the device operates only with an information signal. After processing the received data, the ECU controls the fan relay mounted on the radiator. The main advantage of such a scheme is the possibility of emergency operation of the cooling system in the event of a break in communication with the sensor or its failure. The ECU can also adjust the engine's operating mode by influencing the injectors.

To determine the location where the fan on sensor is located, you need to pay attention to the thermostat. In injection engines, they are located side by side. In some car models, wires go from the sensor to the dashboard to indicate the status of the device or to display the current coolant temperature.

Checking the performance of the sensor

Checking the performance of the device should begin with monitoring the response temperature. This will require a thermometer and a multimeter. All actions can be performed independently, without resorting to a visit to the service center. If the multimeter is equipped with a thermocouple, then there is no need for a thermometer. To check the sensor, follow the instructions below:

If there is a critical deviation of the response limit, the sensor must be replaced. After purchasing a new device, it must be checked for suitability. Defective products are very common on sale, so checking whether the sensor turns on correctly is the responsibility of every car owner.

Replacement with antifreeze drain

If the device malfunctions or is completely inoperable, it is required to replace it with a new one. To perform dismantling, follow the instructions:

1. If the engine is hot, let it cool down;
2. Disconnect the "mass" of the car by disconnecting the negative terminal of the battery;
3. Remove the cover of the expansion tank;
4. Remove the radiator cap ;
5. To prevent contamination, it is required to substitute a container under the drain hole;
6. Drain the antifreeze from the radiator. There is no need to drain antifreeze from the cylinder block. To unscrew the drain plug, hand effort is enough, so no tools are needed;
7. When the liquid stops flowing out, the plug should be returned to its place to avoid its loss;
8. Remove the terminal with wires;
9. Loosen the sensor carefully with a wrench.

To install a new sensor, you must:

1. Check the condition of the copper sealing washer. In most cases, it will require replacement with a new one. Using an old gasket is fraught with smudges of antifreeze;
2. Screw in the new sensor, making sure that the sealing washer fits evenly;
3. Connect terminals with wires;
4. Pour antifreeze into the expansion tank. If the drained antifreeze is of good quality, then you can return it. Otherwise, fresh liquid must be used;
5. To eliminate air locks in the cooling system, it is required to purge it;
6. Replace the radiator cap;
7. Close the expansion tank;
8. Connect the negative terminal of the battery;
9. Warm up the engine until the sensor trips.

If after the above actions the fan does not turn on when the required temperature is reached, it is necessary to continue troubleshooting in other possible places. Before continuing the search for a breakdown, it is advisable to read the error log from the computer using a diagnostic scanner.

Installing a new sensor without draining the coolant

In the injection engine of most car models, the sensor is located high in the cooling system, which allows it to be removed without a significant spill of antifreeze. To do this, you must follow the instructions below:

1. Unscrew the sensor completely. In this case, a slight seepage of antifreeze will begin;
2. Check the copper washer on the new sensor;
3. Unscrewing the old device with one hand, quickly bringing the new one with the other;
4. After tightening the regulator, carefully wipe the place from coolant drips;
5. Check the quality of the installation for leaks.

With this method, the car owner can significantly save time. The disadvantage of this method is the need to replace quickly, which can cause difficulties for inexperienced motorists. In an unfortunate set of circumstances, a large amount of antifreeze can spill out of the cooling system.

The design and circuit diagram of the radiator fan may differ not only depending on the brand of the car, but also on the year of manufacture and model configuration. Consider not only the principle of operation, but also the connection option with the possibility of forcibly turning on the cooling system fan (HCO).

Features of the design of the cooling system

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

• with the help of a power sensor for activating the VSO. Such a sensor is also called a temperature switch for turning on the fan, since the power contacts of the electric motor pass directly through the sensor. With such a scheme, the load on the thermal relay increases significantly, which reduces its resource;
• using the fan on sensor, but now the closure of the contacts in the temperature switch triggers the relay, through which the power contacts of the cooling system electric fan are connected. This connection method is much more reliable than the previous version;
• using the electronic engine control unit. The ECU, guided by the coolant temperature sensor installed in the engine cooling radiator, supplies power to the VCO through the relay. A resistive temperature sensor is used as a meter. It is this switching scheme that is used on the vast majority of modern cars. On machines 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

Understanding the principle of operation and the connection diagram of the radiator fan, it should be remembered that electric motors often have two speed modes. This is implemented in 2 ways:

• adding a resistor to the circuit that increases the resistance and, as a result, reduces the current strength. The design uses a two-contact sensor, which, depending on the temperature, feeds the electric motor directly or through resistance;
• combination of parallel and series connection. The scheme is used on a car with two fans. They can be connected in series, in which case, according to Ohm's law, they will work from 6 V, or in series, when 12 V is applied to each of the VSO. The modes correspond to low and high propeller speeds.

Circuit options

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

As we can see, the sensor controls the relay to turn on the fan, 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 motor circuit.

Above is a diagram for a VAZ 2108, 2109, 21099 car, but after 1998 onwards. As we can see, the switch-on sensor now functions as a relay.

We will consider a scheme using a resistor to implement two propeller speeds using the VW Passat as an example. The two-position fan power sensor S23, depending on the temperature of the coolant, closes the contacts directly or through an additional resistance.

DIY connection

Some drivers, warning the engine against malfunctioning of the radiator fan power supply thermostat, make a remote button to force the 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 relay to operate. If the design of the car does not provide for a fan relay, you will have to install it yourself to force the radiator to cool.

In no case do not connect the electric motor directly through the button in the passenger compartment! We also do not recommend connecting the circuit so that after the ignition is turned on, the electric fan constantly rotates, as this significantly reduces its resource.

To connect, you just need to understand the principle of operation of a 4-pin relay and minimal knowledge in installing additional equipment. Be sure to include a fuse of the required rating in the power circuit and place it as close as possible to the power source (details on).

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