2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:42
Any internal combustion engine requires proper cooling. Without it, the motor will simply overheat, as a result of which the moving elements will instantly fail. The engines of modern cars are equipped with a liquid cooling system, which provides for constant circulation of the coolant (coolant), achieved through the operation of a water pump (pump). Whatever coolant is used in the engine, prolonged heating will invariably lead to boiling. To prevent this process, a radiator is used in the cooling system. It is a system of thin tubes equipped with special lamellas that increase the area of the cooler.
When the car is in motion, the air flow enters the working surface of the radiator and passes between the lamellas, cooling the metal. Thus, the coolant temperature gradually decreases.
However, the radiator alone cannot cope with overheating, especially if the car is stationary or moving at low speeds. He is assisted in this by an electric fan that turns on automatically when the coolant reaches a certain temperature.
When it fails, the engine inevitably faces overheating with all the ensuing consequences. In this article, we will talk about the possible reasons why the cooling fan does not turn on, as well as how to identify and fix related problems.
What is a radiator fan
For starters, let's say that all the information provided is more intended for VAZ owners, although it can also be useful for drivers of foreign cars.
The VAZ cooling fan is an ordinary electric motor powered by 12 V from the car's on-board network. Its shaft is equipped with an impeller that forms a powerful air flow and directs it to the working surface of the radiator. The fan on a special frame (frame) is attached to its front part. Behind it is protected by a radiator grille.
Most VAZ vehicles are equipped with one fan. But there are exceptions. For example, the NIVA cooling fan has two independent electric motors with an impeller that turn on simultaneously. This is necessary so that the engine of the domestic SUV cools faster.
How the fan turns on
Turning on the device in different models is different. In cars with carbureted engines, it starts after the coolant reaches a certain temperature (105-107 0С) and the fan on sensor (not to be confused with the coolant temperature sensor) is triggered, sending a signal to the relay. It closeselectrical circuit, supplying power to the electric motor.
The cooling fan circuit for machines with an injector is slightly different. Here everything is controlled by an electronic unit. The information from the activation sensor is first analyzed by the controller, and only then transferred to the relay.
Possible fan malfunctions
If the fluid temperature has reached a critical level, but the radiator cooling fan does not work, then there is a problem somewhere. Our task is to find it and eliminate it. Let's denote the most common malfunctions due to which the cooling fan does not work. There aren't many of them.
- Fan motor failed.
- The integrity of the wiring supplying the electric motor or connecting the fan on sensor has been broken.
- Poor contact in motor or sensor connectors.
- The cooling fan fuse has blown.
- Faulty fan relay.
- Faulty sensor.
- Faulty expansion tank safety valve.
Checking the electric motor
If the cooling fan does not work, the first thing to do is to check its drive (electric motor). Make it simple. It is enough to take two wires, connect them to the fan and power them directly from the battery. If it starts, then the problem is not in it. It needs to be looked for further. In parallel, you can check the contacts in the motor connector. Sometimes it happens that the problemis located in them. The ingress of dirt and dust, as well as the oxidation of metal surfaces, can cause poor contact.
If the electric motor does not turn on after connecting to the battery, it is most likely that it has broken. The reason for this may be:
- worn brushes;
- destruction of the collector;
- short circuit of rotor or armature windings.
In the first case, it is enough to replace the brushes with new ones, and the fan motor will work like new again. In the case of the destruction of the collector or the short circuit of the windings, repair may not help.
Checking wiring
Another common malfunction that does not turn on the cooling fan is a violation of the integrity of the wiring. This may be a wire break or a short to ground. You can check the circuit using a conventional car tester turned on in detector mode. In this case, you should “ring out” not only the wire from the sensor to the controller, but also the wiring connecting the controller to the fuse, the fuse to the relay, the relay to the electric motor.
Checking the fuse and fan relay
If the wiring is all right, move on to other equipment. First check the cooling fan fuse. It is usually located in the mounting block under the hood of the car and is labeled F7. We check it with the same car tester. If the fuse is good, move on. We are looking for a fan relay. It is underright panel cover of the center console. There are three relays. The owner's manual of the car will help determine the right one, as different models have different locations.
But how to check the relay? In "marching" conditions, it is almost impossible to determine its performance. It's easier to take an adjacent relay (if its parameters match) and install it in the desired socket.
Testing the fan on sensor
The next reason why the cooling fan does not work may be a faulty sensor. Cases of failure of this element are not so rare. It is possible to accurately determine that it is the sensor that has broken down only in a car with an injection engine. If you disconnect it from power, the electronic control unit will perceive this as a system malfunction and start the fan in emergency mode.
Verification is carried out as follows. We warm up the car until the temperature of the coolant reaches 100 0С, after which we turn off the engine, raise the hood and turn off the sensor by disconnecting the connector on it. After that, we start the engine. If the fan turns on, then the problem is with the sensor.
Unfortunately, this check is not possible in cars with carbureted engines. Here you can determine the operability of the fan on sensor only by replacing it with a new one and warming up the engine to operating temperature.
Changing the safety valve
There is another problem that may cause the system to malfunction. If it doesn't workcooling fan, even after confirming the operability of all the listed elements of the chain, it is worth checking the safety valve on the expansion tank.
The role of this valve is to maintain the working pressure in the system above atmospheric pressure. This is necessary so that the water that is part of the coolant does not boil when heated to 100 0C. If the safety valve fails, the pressure in the system will equalize with atmospheric pressure, and the liquid will boil, reaching the boiling point of water.
The switch-on sensor, as already mentioned, can only turn on at 105-107 0С. Thus, our coolant will boil, but the fan will not work.
How to check the safety valve? At home, this is not possible. It's easier to buy a new valve, especially since it costs a penny.
Helpful tips
Finally, check out some useful tips that will allow you, if not to avoid problems with the timely turning on of the cooling fan, then at least improve the situation a little.
- Regularly check the operation of all elements of the cooling system. Pay attention to the coolant temperature readings on the instrument panel, and also listen to see if the fan turns on.
- Watch the coolant level in the system. Replace it in time.
- Rinse the cap of the expansion tank at least once a year under running waterwater. This solution will extend the life of the safety valve.
- If there is the slightest malfunction in the cooling system, stop driving and take corrective action.
- If the cooling fan does not work due to the failure of the sensor, fuse or relay, and this malfunction caught you on the way, turn off the sensor (for the injector) or connect the electric drive directly to the on-board network (for the carburetor). This way you can drive to the nearest service station without the risk of engine overheating.
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