The VAZ 2107, as a representative of the VAZ “classic”, has a fairly loud cooling fan. The moment of its connection cannot be missed. The vibration of the body increases, a hum is heard from under the hood, if the turn-on time coincides with an increased load on the electrical network (blinking turn signals when the low beam is on, heated rear window) - then the arrow of the load on the power network begins to slide into the red zone.
And even (if the carburetor is poorly adjusted), the emergency oil pressure light 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 when a certain temperature in the system is reached. 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, first the “small circle” of antifreeze is heated, then the cooling circuit provides for the passage of liquid through the radiator, the work of which is intensive heat exchange. And only when the temperature rises above 92 C°, the fan switch sensor is triggered.
About forced fan activation
The cooling circuit does not provide for constant fan operation. But in some cases it is possible to implement the principle of “forced fan connection”.
This is done if the sensor has failed and replacement on the road is impossible. You can check this as follows: the engine temperature controller has already shown the vertical position of the needle on the dial, it persistently “climbs” into the red zone, and the fan is silent and does not turn on. If this is the case, then there are most likely two possible reasons:
- The sensor itself, which turns on the fan of the VAZ 2107, has failed. This situation is more favorable than that described below. Firstly, the cooling circuit is complete, and the radiator works 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:
- If there is a straight road ahead and the car will move without stopping, then you can monitor the temperature scale. In case of traffic jams or traffic lights, you can turn on the stove at full power at double blowing speed.
- You can decide to install forced fan activation. To do this, two contacts are pulled out of the controller and short-circuited. Attention! Before this, you must first remove the “minus, ground” from the battery. After the wires are short-circuited, the negative terminal is connected again, and the Carlson begins to work constantly, regardless of the engine temperature and the vehicle’s driving mode. After stopping the VAZ 2107, the fan will work until the battery is discharged, so after stopping you need to open the hood and disconnect the negative terminal.
This is very annoying for owners of a VAZ 2107 with central locking and an alarm system, 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 get under the working impeller blades, because the layout of all the wires in the engine compartment is supposed to be in harnesses. Of course, it’s inconvenient to drive like this for a long time, because constantly opening and closing the hood to connect and turn off will get boring. In addition, no one will like constant noise, vibration and increased wear on the fan axis bearings. Forced activation is an emergency method.
How to remove and install a new sensor
After purchasing and checking the controller, you need to do the following:
- Disconnect the negative terminal from the battery;
- Remove the cover of the cooling distribution tank and the cap from the radiator;
- We substitute the container, turn off the tap on the radiator and drain the antifreeze;
- Having removed the wires from the sensor, use a 30mm wrench to unscrew the sensor by the large brass nut;
- Next, the sensor is removed. Be careful not to drop the copper O-ring on the sensor.
After this, the sensor is replaced with a new one. When installing, do not forget to coat the contact areas of the sensor and radiator with a layer of high-temperature sealant before screwing the sensor. This must be done dry. This scheme of action allows you to avoid leakage of antifreeze.
- Now you need to tighten the cap on the radiator, fill in the collected antifreeze, and, by connecting the negative terminal to the battery, check the operation of the sensor and fan. Do not forget to push through the air pockets in the cooling lines of the VAZ 2107.
That's it, you can hit the road! The fan will run.
Hello everyone, today I would like to talk about why the fan on a VAZ 2107 car does not work. As you probably already know, two types of engines were installed on VAZ 2107 cars: a carburetor and an injector. Therefore, the voltage supply circuits to the cooling fan motor will be different. On a VAZ 2107 injection engine, a two-contact fan sensor, which is located in the upper pipe, when the coolant temperature rises above that for which it is designed, it should send a signal to the computer. The electronic control unit, having analyzed the signal, turns on the fan through a relay.
Therefore, the first step when troubleshooting is to remove the connector from the sensor. If the fan itself is working, then it should work. By inserting a load in the form of a light bulb into the connector terminals, it should stop. With this technique you check the circuit of the fan motor of a VAZ 2107 car. Therefore, if necessary, the sensor will have to be replaced.
Injection engines
Here everything is somewhat more complicated, since the following devices are responsible for the operation of the radiator electric motor:
- Electronic control unit.
- Coolant temperature sensor.
- Electromagnetic relay.
The reason why the electric fan may not work (or often turn on too much) lies in one of these components. Of course, the engine starts too often if the radiator honeycombs, either inside or outside, are very dirty, or if there are air pockets. But it does not turn on due to a breakdown in the control system.
So, you need to find a temperature sensor for diagnostics. It is located in one of the pipes of the VAZ 2107 engine cooling system. If you look at the engine from above, you will find it under the pipe that connects the fuel rail to the throttle valve. To check it, you need to disconnect the terminal and measure the resistance between the central terminal and ground. At a temperature of 20 degrees, the resistance should be about 3.5 kOhm. If the temperature is close to 90 degrees, then the resistance will be about 0.25 kOhm.
If there is no resistance, or it differs significantly from the values given above, then there is clearly a malfunction of the sensor and it cannot be repaired. The price of a new one will be approximately 100-200 rubles (depending on the seller’s appetite). But if the sensor is working, but the electric fan does not work, then you need to check its electric motor and switching relay. If no problems are found, diagnose the electrical wiring.
If this does not work, you will need the help of a competent auto electrician. Most likely, the firmware has gone wrong or part of the electronic control unit circuit has burned out. If there are no other troubles, then instead of an expensive replacement of the ECU it will be easier to install an electric fan switch sensor, since there is space in the radiators for its installation.
Perhaps this is where the troubleshooting can be completed. This algorithm will be enough to repair the cooling system. In the same case, if it is not possible to replace the relay or sensor, for example, simply connect the electric fan to the battery. Only after stopping be sure to turn it off.
Electric cooling fan operation
The design of the “classic” cooling system does not provide for constant fan operation. It should turn on only after reaching a certain coolant temperature, we discussed this in more detail in this article. The fan switching sensor for the VAZ 2107 injector is installed in the radiator. Therefore, the fan turns on after the radiator itself can no longer cope with the cooling task. This is implemented as follows:
- After heating the antifreeze in the “small circle” of cooling, the thermostat opens.
- The coolant circulates in a “large circle” through the radiator, which ensures effective heat exchange with the environment.
- If the radiator does not “cope” with cooling, the contacts of the fan sensor close and it begins to intensively drive air flow through the radiator, increasing heat transfer.
If the sensor fails, the fan turns on when it overheats and the coolant may boil.
VAZ 2107 fan sensor malfunctions and performance check
It is easy to find out whether the VAZ 2107 fan switch sensor is working properly. The fan motor is quite noisy; you can hear it turning on even from inside the cabin. If the temperature gauge shows more than 90 degrees, but the fan does not turn on, you should check the sensor.
First you need to localize the source of the problem. If the antifreeze is hotter than 90 degrees, but the bottom of the radiator remains cold, the problem is the thermostat, not the fan. It is not possible to replace the thermostat on the road. To get out of the situation, you can increase the cooling by fully opening the heater damper and turning on its fan. Of course, such a solution will be extremely uncomfortable in the warm season, but, if you’re lucky, it will make it possible to get to the repair site without stopping. If this is not enough, you will have to make stops along the way to allow the engine to cool.
Another reason for overheating is low coolant level. In this case, it is necessary to quickly find and eliminate the leak and add antifreeze to the system. If it is not there, you can add water to the system. But then, as soon as possible, it is necessary to drain the liquid from the cooling system and add antifreeze.
Forced fan activation
If the VAZ 2107 fan sensor is broken, it is quite possible to drive on a good road without noticing it. But as soon as you drive onto a country road or get into city traffic jams, the engine will start to overheat. Replacing the fan sensor is not very difficult, but requires draining the coolant. Even if you have a spare sensor at hand, replacing it on the road is problematic. There is an easier way out of the situation.
The following operations must be performed:
- disconnect “mass”;
- remove two wires from the sensor terminals and connect (“short-circuit”) them;
- insulate the exposed contacts of the connected wires;
- connect ground.
In this case, the fan will run continuously. To turn it off, you will have to disconnect the ground and disconnect the contacts.
If you have already experienced problems with the fan sensor on the road, you can install a forced fan circuit on the car that operates in parallel with the sensor. To do this, just connect a couple of wires to the terminals going to the sensor contacts and stretch them into the engine compartment. Install a separate button (toggle switch) on the dashboard and connect the wires to it so that you can close them if necessary.
In this case, if the sensor malfunctions, there will be no need to crawl under the hood to force the fan to start.
Where is the fan switch located?
For all outdated modifications of the “classic”, the sensor is located on the cooling radiator housing. Bottom right to be precise. From the outside, it looks like a brass nut “30” with two contacts out. Raise the hood and look at the back of the radiator. you will definitely see him. The principle of operation of the sensor is very simple. The thermocouple reacts to an increase in temperature, closes the contact, and voltage is supplied to the fan. For vehicles with controlled fuel injection, the fan is turned on by a command from the electronic unit based on data received from the sensor. In other words, the ECU itself controls all processes. But where is the fan switching sensor located on injection-powered “sevens”?
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Replacing the VAZ 2107 fan sensor (injector)
The procedure for replacing the sensor is as follows:
- disconnect the ground wire from the battery;
- remove the radiator cap and expansion tank cap (to avoid steam burns, do not open the cap on an overheated engine);
- place a container under the radiator drain hole;
- unscrew the plug (or turn the drain valve) and drain the antifreeze from the radiator;
- remove the wires from the sensor contacts;
- Unscrew the VAZ 2107 fan sensor (injector) with a wrench;
- check the condition of the copper sealing washer under the sensor and replace it if necessary;
- screw in the new sensor (don’t forget to put the sealing washer);
- pour antifreeze into the cooling system (it is better to pour new one, but you can also use previously drained one if it is clean and transparent);
- connect ground to the battery and start the car;
- with the engine running, press the rubber hoses of the cooling system with your fingers to remove air pockets;
- install the radiator cap and expansion tank cap;
- Warm up the engine to operating temperature and make sure the sensor is working.
After this, the car is ready for use.
Check and replacement
If you suspect that the engine is overheating and there is no sound from the fan for a long time, it is necessary to determine the malfunction. If the wiring is shorted, the device may fail or the fuse may blow.
Checking the device is easy. You need to remove the wiring from the sensor, turn on the ignition key and connect the ends. If the cooling works, then there is a problem with the device and it needs to be replaced. It happens that cooling turns on at temperatures higher than those indicated on the sensor body, which also indicates its malfunction.
To replace it, you will need to drain the antifreeze or rush to screw in a new sensor, spilling a little coolant. The engine must be cold. You can unscrew it with a wrench or an adjustable wrench. It is better to substitute some kind of container and use a wrench to undermine the housing nut. Then carefully unscrew the thread by hand, pressing it against the socket. Move the old device aside and quickly press it with your finger, maybe some kind of plug, on the hole in the radiator. Carefully screw in the purchased sensor and connect the wiring.
