The design of any modern car consists of many different components and mechanisms. One of these is the engine cooling system. Without it, the motor would endure constant overheating, which would ultimately disable it. An important component of this system is the radiator cooling fan. What is this part, how is it arranged and what is it for? The answer to this question is further in our article.
Characteristic
The radiator cooling fan is a part that provides forced air circulation for the engine. Due to the uniform and constant removal of heat from its elements, the temperature of the internal combustion engine always remains within the operating range and rarely exceeds +95 degrees Celsius.
Varieties
There are two types of constructions for these elements:
- Electric.
- Mechanical
The latter type works due to V-belt transmission of forces from the crankshaft pulley. As for the electric, such a radiator cooling fan is driven by a special motor. Also, this design requires a separate control system. The intensity of this element directly depends on the temperature sensor.
Device and principle of operation
At the moment, it is customary to distinguish between three types of fans:
- With viscous coupling.
- With thermal switch.
- With ECU (electronic control unit).
As for the first type, viscous coupling systems are almost never found on cars. Basically, they were installed on cars with a longitudinal engine or on massive all-wheel drive SUVs, which also overcome water obstacles. The viscous coupling responsible for the rotation of the fan is completely tight. This design allows you to protect it from the effects of external factors, including water. By the way, electric fans immediately break down after entering the fluid block. They are no longer subject to further repair and restoration.
The viscous coupling is filled with silicone oil. The latter, when exposed to high temperature, changes its properties and, depending on the level of heating, increases or decreases the rotation speed of the fan. The design of the viscous coupling assumes the presence of such details as a package of drives of the driven and drive shafts, as well as a sealed housing with gel or oil.
How does it all work? The principle of operation of this element is based on the transmission of rotational movements from the drive shaft due to disk packs. The latter are placed in silicone fluid, that is, in gel or oil. The viscosity of these components, as we said earlier, varies with temperature.
Power Elements
As for electrically driven fans, they consist of the following elements:
- Electric motor.
- Electronic control unit.
- Temperature sensor.
- Fan on relay.
More modern units have in their design two temperature sensors, one of which is installed in the pipe leaving the radiator, and the second in the thermostat housing. Sometimes it is mounted in a pipe that exits the engine. The electronic unit, depending on the difference in readings of these two sensors, controls the intensity of rotation of the impeller. And it drives the electric motor of the radiator cooling fan.
For the correct operation of this motor, it is also important to have an air flow meter and a device that will monitor the frequency of the crankshaft (DPKV). After the control unit has received a short signal from all sensors, information is processed and the electronics activate a relay that includes a fan. During its operation, the system controls the number of rotations and can increase or decrease the rotational speed of the impeller. A similar design is now used on most passenger cars and SUVs.
Devices with thermal switch
Before the advent of electronic systems, all machines were equipped with fans with a thermal switch. It was this element that performed the function of turning the impeller engine off and on.
The principle of operation of such a system is as follows. From the temperature sensor, which is installed in the engine block housing, a signal is sent to the scale, which is located in the cabin. Further, depending on the readings and the degree of reaction of the liquid in the radiator to thermal changes, the fan is turned on or off.
As soon as the temperature of the cooler rises to a certain value, the contacts connected to the impeller power circuit are closed inside the thermal switch. Further, an electric current is supplied to the motor, so that the fan starts to rotate. After the temperature of the antifreeze drops again, the contact opens and, accordingly, the impeller stops working.
How to find the cause of an element breakdown?
As we said in the introduction, a fan malfunction can cause frequent overheating of the power plant. Therefore, the driver must regularly monitor its performance and in case of failure, immediately eliminate it.
How to check this part for serviceability? First, remove the plug from the temperature sensor. If this element is single, you should check its serviceability. It is not difficult to do this - it is enough to simply manually close the terminals in the plug with a small piece of wire. If the temperature sensor is double, then to check it, you must first close the white-red, and then the red wire. Ideally, the radiator cooling fan should slowly spin after that.
Next, you need to close the red and black wires. In this case, the impeller should rotate as fast as possible.
But what if the radiator cooling fan does not turn on even after several attempts to close? Conclusion - the temperature sensor is malfunctioning or the fuses are blown. The latter are verified as follows. In the fan connector, a white-red or black-red wire is supplied with current from the battery terminal with a positive charge. At the same time, power is supplied to the brown wire from the negative terminal of the battery. If the radiator fan of the cooling system after these manipulations did not work, then it is time to replace the impeller itself. In another case, it is recommended to inspect all the connectors and plugs that go from the temperature sensor to it.
What to do if the radiator cooling fan does not turn off?
If the unit is immediately put into operation at startup and never shuts down (and this should not be), this indicates a breakdown of the unit's on-switch sensor. How to check this item for serviceability? To do this, turn on the ignition and remove the wire end from the sensor. After that, the fan should turn off. If the impeller still continues to operate, the sensor should be replaced. It should also be remembered that with such symptoms, the radiator cooling fan motor is in absolutely working condition, and it is not practical to check it in this case. But it may happen that the source of the malfunction is the oxidized terminals. When diagnosing them, they should also be examined and, if necessary, cleaned contacts.
Is fan repair possible?
In some cases, it makes no sense to completely replace the part with a new one, since the malfunction can be completely insignificant. It will be much cheaper to repair it with your own hands.
Before you remove the part from the mounts, it is recommended to disconnect the negative terminal of the battery and remove all wires that go to the fan. Then you need to unscrew the fasteners of the device and take it out.
In some cases, it happens that the culprit of the malfunctions is banal dirt. Therefore, after successful dismantling, the fan blades are thoroughly cleaned of dust and other deposits. This is best done with a brush.
In addition, damage may result from poor wire contact. This phenomenon occurs due to the oxidation of elements in the connecting plugs. Next, you need to check the operability of the rotor winding. Sometimes the radiator cooling fan does not work due to a short circuit or break in this part of the system. In this case, you should inspect each turn.
However, there are elements in the design of this unit that cannot be restored. In addition to temperature sensors, the electric motor of the radiator cooling fan is not subject to repair. What indicates its malfunction? The inoperative state of an electric motor can be determined by the state of operation of the impeller. If during overheating of the power plant it does not turn on, most likely, the radiator cooling fan motor has become unusable. In this case, it is urgent to replace it.
Other malfunctions
All motorists know that the radiator cooling fan (VAZ 2110-2112 can be taken as an example) is a source of increased noise and vibration. But if this sound of his work exceeds the maximum norm, so much so that the engine itself is not audible, this indicates a number of malfunctions. So, why does the cooling fan of the radiator of VAZ cars make a noise? There may be several reasons:
- Unscrewed bolt securing the impeller to the pulley (screw the part).
- Broken part of the blade (replace fan).
- Lack of lubrication on the electric motor.
- Broken bearing (replacement only).
Conclusion
So, we found out why the radiator cooling fan does not work, and also examined how to diagnose and repair it.
As you can see, this unit is of great importance for the car. Its breakdown will certainly make itself felt in the form of regular engine overheating. But after the first such malfunction, the risk of failure of parts of the cylinder-piston group increases significantly. Therefore, do not put off this problem until later.