The cooling fan does not work. Causes, repairs

Any internal combustion engine requires proper cooling. Without it, the engine simply overheats, resulting in mobile elements immediately out of order. The engines of modern cars are equipped with a liquid cooling system that provides for the constant circulation of coolant (coolant), achieved by the operation of a water pump (pump). Whatever the coolant is not used in the motor, its prolonged heating will invariably lead to a boil. To prevent this process, a cooling system is used in the cooling system. It is a system of thin tubes equipped with special lamellae that increase the area of the cooler.

When the car is in motion, the airflow enters the working surface of the radiator and passes between the lamellae, cooling the metal. Thus, the temperature of the coolant gradually decreases.

However, the heatsink alone can not cope with overheating, especially if the car is standing or moving at low speeds. It is assisted by an electric fan that turns on automatically when the coolant reaches a certain temperature. If it fails, the engine will inevitably face overheating with all the ensuing consequences. In this article, we'll talk about the possible reasons why the cooling fan does not turn on, and how to identify and fix the related malfunctions.

What is a radiator fan

First, let's say that all the information provided is more intended for VAZ owners, although for drivers of foreign cars it can also be useful.

The VAZ cooling fan is an ordinary electric motor with 12 V supply from the vehicle's on-board network. Its shaft is equipped with an impeller, which forms a powerful stream of air and directs it to the working surface of the radiator. The fan on a special frame (frame) is attached to the front part. At the rear it is protected by a radiator grille.

Most VAZ cars are equipped with a single fan. But there are exceptions. For example, the cooling fan "NIVA" has two independent electric motors with an impeller, which are switched on simultaneously. This is necessary in order for the domestic SUV engine to cool more quickly.

How the fan turns on

The inclusion of the device in different models occurs in different ways. In cars with carburetor engines, it starts after reaching the coolant temperature (105-107 ⁰ C) and the activation of the fan switch (not to be confused with the coolant temperature sensor ), which sends a signal to the relay. It also closes the electric circuit, feeding power to the electric motor.

The cooling fan circuit for the machines with the injector is slightly different. Here everything is controlled by an electronic unit. Information from the switch-on sensor is first analyzed by the controller, and then transferred to the relay.

Possible fan malfunctions

If the temperature of the liquid has reached a critical level, but the radiator cooling fan does not work, then there is a problem somewhere. Our task with you is to find it and eliminate it. Denote the most common faults, due to which the cooling fan does not work. There are not so many of them.

1. The fan motor has failed.
2. The integrity of the wiring that feeds the electric motor or connects the fan switch is broken.
3. Unreliable contact in the motor or sensor connectors.
4. The fuse of the cooling fan is blown.
5. Defective fan relay.
6. The sensor is defective.
7. Disturbances in the operation of the safety valve of the expansion tank.

We check the electric motor

If the cooling fan does not work, first of all it is necessary to check its drive (electric motor). Make it simple. It is enough to take two wires, connect them to the fan and power directly from the battery. If it starts, then the problem is not in it. It should be looked for further. In parallel, you can check the contacts in the motor connector. Sometimes it happens that the problem is in them. The ingress of dirt and dust, as well as the oxidation of metal surfaces can cause contact breakage.

If the electric motor does not turn on after connecting to the battery, it is likely that it broke. The reason for this may be:

• Worn brushes;
• Destruction of the reservoir;
• Closing of the windings of the rotor or armature.

In the first case, it is sufficient to replace the brushes with new ones, and the fan motor will again work as a new one. In the case of the destruction of the collector or the closure of the windings, repairs may not help.

Check the wiring

Another common malfunction, which does not include the cooling fan, is the integrity of the wiring. This can be a wire break or a short to ground. The chain can be checked using a conventional car tester, which is switched on in detector mode. In this case, it is necessary to "ring" not only the wire from the sensor to the controller, but also the wiring connecting the controller to the fuse, the fuse with the relay, the relay with the electric motor.

Check the fuse and the fan relay

If everything is in order with the wiring, we turn to other equipment. First check the fuse of the cooling fan. Usually it is located in the mounting block under the hood of the car and is marked F7. We check it with the same car tester. If the fuse is sound, go ahead. We are looking for a relay to switch on the fan. It is located under the cover of the right panel of the center console. There are three relays. Determine the necessary help guide the car, as different models have different layouts.

But how to check the relay? In "marching" conditions it is practically impossible to determine its working capacity. It's easier to take a nearby relay (if its parameters match) and set it to the correct socket.

Test the fan switch

The next reason why the cooling fan does not work can be a faulty sensor. Cases of failure of this element are not so rare. It is only possible to determine exactly what the sensor has broken in a car with an injector engine. If you disconnect it from the power supply, the electronic control unit will take this as a malfunction of the system, and will start the fan in emergency mode.

The verification is as follows. Warm up the car until the temperature of the coolant reaches 100 ⁰ C, after which the engine is muffled, raise the hood and turn off the sensor, disconnecting the connector on it. After that we start the engine. If the fan turns on, then the problem is in the sensor.

Unfortunately, such a test is not possible in cars with carburetor engines. Here it is possible to determine the efficiency of the fan switch by replacing it with a new one and warming the engine to operating temperature.

We change the safety valve

There is one more malfunction, which can lead to a malfunction in the system. If the cooling fan does not work even after confirming the operability of all 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. This is to ensure that the water that forms part of the coolant does not boil when heated to 100 ^° C. If the safety valve fails, the pressure in the system will equalize with the atmospheric pressure, and the liquid will boil to the boiling point of water.

The switch-on sensor, as already mentioned, can only switch on at 105-107 ^° C. Thus, our cooling liquid will boil, but the fan will not work.

How to check the safety valve? At home, this is impossible. It's easier to buy a new valve, especially since it costs a penny.

Helpful Tips

Finally, get acquainted with useful tips that will allow you, if you do not avoid problems with the timely inclusion of a cooling fan, then at least a little to remedy the situation.

1. Systematically check the operation of all elements of the cooling system. Pay attention to the coolant temperature on the instrument panel, and also listen if the fan turns on.
2. Watch the level of coolant in the system. Do it in time.
3. At least once a year, flush the cap of the expansion tank under a stream of running water. This solution will prolong the life of the safety valve.
4. If there is a slight malfunction in the cooling system, stop moving and take corrective measures.
5. If the cooling fan does not work due to a failure of the sensor, fuse or relay, and this fault has caught you en route, disconnect the sensor (for the injector) or connect the drive directly to the on-board network (for the carburetor). So you can reach the nearest service station without the risk of engine overheating.