We independently change the fan switch sensor on the VAZ 2107: sequence and recommendations

Not a single internal combustion engine can function without proper cooling, and the VAZ 2107 engine is no exception in this sense. If a problem occurs in the cooling system, then overheating of the motor is a matter of several minutes. Often the source of the problem is the fan on sensor. Fortunately, the car owner may well replace it with his own hands. Let's try to figure out how it's done.

The purpose of the VAZ 2107 fan switch-on sensor

The purpose of the sensor is easy to guess from its name. This device is responsible for the timely inclusion of a fan that blows over the main cooling radiator.

VAZ 2107 fan sensors have a monolithic housing and small dimensions

Additional airflow is required when the antifreeze in the radiator heats up to a temperature above 90 ° C and the engine stops cooling normally. As a rule, this happens in the warm season when driving around the city or on country roads.

Designs and principles of operation of sensors

Over the years, various models of fan switch sensors were installed on VAZ 2107 cars. At first, these were electromechanical sensors, then they were replaced by electronics. Let's consider each device in more detail.

Electromechanical sensor VAZ 2107

Inside the electromechanical sensor is a small container with ceresite mixed with copper powder. Above this substance is a flexible membrane with a pusher attached to it. And the pusher, in turn, is connected to a moving contact. This whole structure is housed in a steel case with thick walls (which are necessary to ensure more uniform heating of the sensor). On the outer part of the case there is a thread and a pair of electrical contacts.

The operation of the electromechanical sensor VAZ 2107 is based on the expansion of ceresite under the influence of high temperature

The sensor is based on a simple principle: the volume of ceresite changes with increasing temperature. Ceresite, warming up under the action of almost boiled antifreeze, expands and raises the membrane, which sets the pusher in motion. It reaches the moving contact and closes it, causing the fan to turn on. When the antifreeze temperature drops due to additional blowing, the ceresite cools down, the membrane goes down, the contact opens and the fan turns off.

Electronic sensor VAZ 2107

The basis of the electronic sensor is a thermal resistor inserted into a massive steel case. As in the previous case, the case has a thread that allows you to screw the sensor into the radiator, and a pair of contacts.

The main element of the electronic sensor VAZ 2107 is a thermistor

The operation of an electronic sensor is based on a change in the resistance of a resistor under the influence of high temperature. Changes in electrical resistance are tracked by a special circuit. And when the resistance reaches certain values, the circuit sends a signal to the contact system, they close and turn on the fan.

Sensor location

On almost all classic VAZ models, the fan switch sensors are screwed directly into the cooling radiators. This is necessary so that most of the working surface of the sensor is in contact with hot antifreeze. Between the sensor and the radiator, a special sealing gasket made of a material resistant to high temperatures is installed without fail.

The red arrow indicates the VAZ 2107 fan sensor, the blue arrow indicates the sealing ring under it

Since the VAZ 2107 fan sensor is screwed into the lower part of the main radiator, it is most convenient to change it from the inspection hole on which the car must be installed.

Checking the performance of the fan sensor VAZ 2107

To check the health of the fan on sensor on the VAZ 2107, you will need the following things:

• a container for boiling water;
• thermometer;
• household boiler;
• fan switch removed from the machine;
• household multimeter.

Sensor Test Sequence

The sensor check sequence is as follows:

1. Water is poured into the prepared container.
2. The threaded part of the sensor is immersed in water, and its contacts are connected to the contacts of a multimeter configured to check electrical resistance.
3. Now the thermometer and the boiler are immersed in the water.
4. The boiler is connected to the network, the water begins to heat up. The heating temperature is monitored by a thermometer.
   

   The VAZ 2107 sensor is immersed in a container of water and connected to a multimeter
5. When the water temperature reaches 95 degrees, the resistance of the sensor should disappear (this will be visible on the multimeter display).
6. If at the above water temperature the resistance disappears, the fan switch-on sensor is considered to be in good order.
7. If the sensor maintains resistance when heated above 95 degrees, it is faulty and must be replaced.

Video: checking the health of the VAZ 2107 fan sensor

https://youtube.com/watch?v=FQ79qkRlLGs

Malfunctions associated with the VAZ 2107 fan sensor

There are a number of the most common problems due to which the fan on the VAZ 2107 may not turn on at the right time, which will lead to engine overheating. Here they are:

• The fan switch sensor has burned out. Most often this happens due to a sharp power surge in the electrical network of the machine, which arose as a result of a short circuit. Wiring on the VAZ 2107 has never been durable and reliable. Over time, it begins to crack and becomes completely unusable, which leads to a closure;
• blown fuse responsible for the fan. There are situations when the fan sensor is working, but the fan still does not turn on. In this case, you need to look into the safety block located under the steering column of the car and find the fuse responsible for the operation of the fan there, remove it and inspect it. If it is melted and slightly blackened, the cause of the malfunction has been found.
  

  Arrow 1 shows the location of the VAZ 2107 fan fuse. Arrow 2 shows the location of the fan relay

Replacing the sensor for turning on the fan VAZ 2107

Fan sensors on the VAZ 2107 cannot be repaired. There are simply no parts that a car owner could buy and replace on their own. In addition, the sensor housing is monolithic and non-separable, so it is impossible to get to the insides of the sensor without breaking it. Therefore, the only thing that a car owner can do if the fan sensor breaks down is to replace it. The following tools and consumables are required to replace the sensor:

• an empty container of 8 liters for draining the coolant;
• open-end wrench for 30;
• 8 liters of new coolant;
• new fan switch.

Operating procedure

When replacing the fan on sensor with a VAZ 2107, proceed as follows:

1. The car is installed above the viewing hole. The plug is unscrewed in the radiator, the antifreeze is drained into the prepared container.
2. With an open-end wrench for 11, both terminals are removed from the battery.
3. Contacts with wires are removed from the fan on sensor. This is done manually, just pull the wires towards you.
   

   To remove the contact wires from the VAZ 2107 sensor, simply pull them towards you
4. The sensor is unscrewed with an open-end wrench by 30 (it should be remembered that there is a thin sealing ring under it, which is easily lost).
   

   To unscrew the VAZ 2107 sensor, an open-end wrench is used for 30
5. The unscrewed sensor is replaced by a new one (when screwing in a new sensor, do not use too much force, since the thread in the sensor socket is very easy to break).
   

   The VAZ 2107 sensor is installed with a sealing ring

Video: replacing the fan switch sensor

Replacing the VAZ fan sensor. Do it yourself!

So, the procedure for replacing a fan sensor with a VAZ 2107 is not particularly difficult even for a novice motorist. If you follow the above instructions, you can save about 600 rubles. This is how much it costs to replace the sensor in a car service.