The structure of the cooling system and how the fan turns on
Before we proceed directly to the temperature at which the cooling fan turns on, it is worth to understand the principle of operation. So, the coolant circulates through the system and transfers the heat from the engine to the radiator. This element, in turn, conducts the natural cooling of the fluid by the counterflow of air.
If there is not enough natural cooling, the fan is switched on. This occurs under certain conditions.
Before looking at all the factors and the temperature of the fan, it is worth understanding the structure of the cooling system and the circulation of the coolant:
cork element for the expansion tank; 2. expansion tank; 3. fluid outlet hose from the socket; 4. hose between the radiator and the expansion tank; 5. exhaust hose from the radiator; 6. tank on the left side of the radiator; 7. aluminum tube; 8. plug systems; 9. tank on the right side of the radiator; 10. drain plug; 11. the middle of the radiator; 12. cover for the electric fan; 13. plastic wings of the electric fan; 14. electric motor; 15. gear pump pulley; 16. pump impeller; 17. camshaft drive belt; 18. engine block; 19. pump pipe; 20. radiator hose with inlet function; 21. radiator hose with outlet function; 22. coolant hose to throttle; 23. outlet pipe; 24. filling hose; 25. heater radiator hose with supply function; 26. thermostat; 27. coolant temperature sensor; 28. coolant level indicator sensor.
What should be the temperature of the engine?
According to the automobile international convention of 1.12.In 1992, where 92 representatives of the automotive industry met, it was decided to set a unified standard for engine operating temperature.
This figure is. 90 degrees Celsius with a maximum permissible deviation of not more than 3 degrees Celsius.
Switching on the cooling fan
But given the region of operation and ambient temperature, this temperature has a tendency to rise. That’s why automakers came up with a cooling system fan, which conducts additional cooling of the fluid in the system. It is driven by a temperature sensor that detects it in the engine and is located directly on the power unit.
When the fan turns on at VAZ-2114
According to the convention and internal normative documents of AvtoVAZ plant, the boundary temperature of the coolant is 85-105 degrees Celsius.
Thus, for normal functioning of the engine system temperature should not rise above 105 degrees. Exactly this parameter is the starting point of switching on the cooling system fan. These data are fed into the electronic control unit, which just regulates the work of the fan.
The scheme for turning on the fan looks something like this: the temperature of the engine reaches 105 degrees Celsius, then the sensor sends a signal to the ECU, which turns on the fan and stops it when the temperature in the system has become 93-99 degrees Celsius.
In summer and winter time, as practice shows, the fan turns on at different temperatures and for different periods. In summer the forced cooling will turn on more often, because the radiator is cooled by the hot air stream. In winter time, the fan almost does not turn on or its work is limited to a small period, because the natural cooling is quite enough. Therefore, the main radiator breakdowns occur in the warm season.
The only nuance, when cooling in winter time will often turn on, if the thermostat is defective (see “Replacement of the Thermostat”). “replacing the thermostat on VAZ-2114”).
It has been determined that the normal operating temperature of the coolant VAZ-2114 is 85-105 degrees Celsius.
In this case, the temperature of cooling fan activation will have a value of 105 degrees Celsius.
VAZ-2114 radiator fan may not turn off due to malfunction of coolant temperature sensor. This device sends information to the ECU about the temperature of antifreeze. If it exceeds 101 degrees, the fan turns on, which should cool it. If the coolant temperature sensor is broken, the electronics get the wrong signal. That’s why the element can work all the time.The sensor is installed in the cylinder head on the intake manifold.
It is not necessary to wire the dipstick to check it. You can borrow a known faulty part and evaluate the operation of the system. If everything works as it should, the sensor should be replaced. Sometimes damage to the element can be noticed visually.
When checking this part, it is not superfluous to inspect the wires and their connections. Sometimes the cause of the malfunction lies in a bad contact or breakage of the wiring. In this case the cleaning of connections from dirt and restoration of the integrity of wires is performed.
At what temperature does the fan switch on the Priora: important features of the thermal mode
The engine of any car, including the LADA Priora, is quite a complex unit consisting of various mechanisms and systems. Stable engine operation is affected by many factors, including temperature conditions.
If the thermal mode of the power unit is insufficient, it will affect the quality of fuel mixture formation in the cylinders. And when the thermal mode will be higher than required, it can lead to jamming of the cylinder-piston group, a serious breakdown and a long and expensive repair.
Purpose of the fan sensor and its place in the car
Coolant On/Off Sensor (FOS). a sensor of the internal combustion engine cooling system, an electronic or electromechanical device that turns on and off the electric radiator cooling fan, depending on the current coolant temperature.
The key function of the sensor. turning on the electric fan in a certain temperature range (between 82-110 degrees), which provides airing of the radiator and intensive heat removal from the engine. The coolant temperature sensor is a type of sensor that not only turns the fan on and off, but also changes the fan speed depending on the temperature.
DVVs are part of cooling systems for engines equipped with an electric fan drive (with electric motor). In autotractor technique with the fan drive from the crankshaft are used other means of turning it on and off, about which this article is not told.
Where is it
Drivers who have never encountered a forced cooling engine malfunction before may not know where the VWW is located. On the VAZ 2110 carbureted car, this element of the cooling system is located on the radiator. If the driver has found this part, he will easily find a sensor to switch on the fan, which is located on the side. A characteristic feature of the product is the electrical wires connected to it. On the injector VAZ 2110 this part can be found on the cylinder block.
The sensor located in this way allows you to react to changes in the temperature of the coolant in a timely manner. In addition, access to this part is not difficult and you can immediately proceed to repair or diagnostic measures, if there are doubts about its performance.
LADA VAZ-2110 (2111, 2112). The engine cooling fan (radiator fan) often blows
Why does the cooling fan always or often turns on?? After all, it is an indication of the bad work of the cooling system. This can lead to overheating of the motor and its failure. This problem is serious enough, in some cases, to fix it you will even need to partially disassemble the engine. The smooth operation of the power unit depends on how quickly you identify the problem. No special skills are required to check and repair, any person can do it. The main thing is to know how to search for the cause of such behavior of the cooling system.
It is obvious from the principle of the cooling fan’s operation that the fan always or frequently blows. It is activated by a sensor located at the bottom of the radiator. This sensor detects an increase in the temperature of the coolant and, as a result, the fan blows. It creates an additional flow of air, which enhances the cooling of the liquid in the radiator and, accordingly, the motor itself. Based on this, it becomes clear, the fan is constantly running, only on overheated power units. To avoid engine failure, it is necessary to react to the problem in time, and fix it.
Engine overheating often occurs due to jamming of this element. The fan reacts by jamming the thermostat halfway open. In this case, the movement of liquid through the system slows down, causing a decrease in efficiency of heat removal. As a result, the engine begins to overheat, respectively, the temperature of the coolant increases. The fan sensor reacts to this. As a result, it works all the time.
Checking the thermostat is simple enough. For this purpose start the engine and warm it up to the temperature of actuation of the thermostat valve. This value is indicated on the housing of the thermostat itself. Wait a little longer, and check the temperature of the upper and lower sockets. If both pipes are evenly hot, then the cause of the constantly working fan has been found. To be on the safe side, carefully inspect the thermostat valve after removing the part from the engine. Fix the problem by replacing the thermostat with a working part.
in many cases, the cause of the coolant temperature increase in the radiator is bad water pump. In this case, the antifreeze moves slowly through the system and gets too hot. Once in the radiator, it does not have time to cool down to normal temperature, and goes on the next circle, heating up even more. If the pump works more or less, such problem is expressed only by the constant work of the fan. If the pump fails completely, it will “boil” in a few minutes. It is an extremely dangerous condition that almost always leaves consequences in the form of problems with the engine.
The water pump does not usually fail suddenly. It first signals its malfunction. The first alarm signal is an increase in the frequency of the radiator fan. The main cause of the failure is the destruction and jamming of the bearing. Therefore, a manifestation of failure can be a howl from under the hood or a knock, heard clearly when idling. Pump knocking is often mistaken for camshaft malfunction. Failure can be eliminated by replacing the pump, some models provide the ability to replace only the front of the pump along with the bearing.
Often it is often caused by blockages in the cooling system. This problem is often difficult to diagnose. Therefore, at the first signs of more frequent activation of the fan without any particular reason, it is necessary first of all to flush the system. This is often sufficient. Also, just in case, you can blow out the radiator.
The radiator and cooling ducts are usually cleaned in conjunction with changing the antifreeze. To flush the system the coolant is drained. Then pour a strong solution of citric acid or water with special additives. Afterwards, let the car run for half an hour. Empty the used cleaning agent and add fresh antifreeze. In most cases this procedure is guaranteed to eliminate impurities in the cooling system.
All motorists know that the radiator is in the front, and is blown by the oncoming wind. Therefore, it gets all the dust and dirt encountered on the road. This dust gradually collects between the radiator plates, significantly reducing the heat transfer. The air flow, in this case, is much worse for cooling the liquid. It gradually heats up to a high level, and causes the fan to turn on.
Repair in this case is simple, you need to clean the radiator. On many modern cars it will have to be removed first, in some cases it is quite possible to get to it without even removing it from the car. It is recommended to wash it with running water. The easiest way to do this is to use a hose. In some cases, it makes sense to clean the radiator with a soft, dry brush before washing. Often such a procedure is combined with a radiator purging.
It is no secret that the cause of fluid overheating is airlocks. They appear as a result of errors in the replacement of antifreeze, as well as due to leaks in the cooling system. As a result, the fluid heats up unevenly, which leads to unstable operation of the fan, with frequent switching on when hotter fluid enters the radiator.
Before fixing it, it is imperative that you check the system for fluid leaks. Having eliminated them, proceed to expel the plugs. For this you will need a compressor. Unscrew one of the coolant pipes from the throttle. Next, you need to connect a compressor to the neck of the expansion tank, and give it compressed air. Usually a couple of minutes is enough to blow out all of the existing clogs.
Many motorists put special heaters on the radiator in the winter, this allows you to reduce the time of heating the car, and save fuel. But, during thaws, the air temperature is high enough. If there is an insulator, the engine is not cooled sufficiently, forcing the fan to work more intensively. To eliminate the cause simply remove the insulation from the radiator.
The cooling system of the machine must always be in good condition. Therefore, the driver needs to keep a close eye on the condition of this system. It is especially important to find the reason, why the cooling fan is constantly working or frequently turns on. This is certainly not a fatal problem, but neglecting this signal can lead to serious engine problems.
Is it possible to drive, if the fan of cooling system is defective?
It is strange, but in some cases it is possible. The fan sucks air through the radiator grille onto the radiator itself, which means that when you drive, the oncoming airflow cools the motor in exactly the same way that the fan does. It is only necessary to switch off air conditioner. it generates excessive heat, and without a fan the air flow can not cope. over, in this case it is not recommended to hit the blind jams. as soon as you stop the cooling disappears and the engine immediately “boils”.
Element serves as a thermostat, but its main purpose is to protect the power unit of the vehicle from excessive heat. When the heating reaches a certain level, a signal must be sent to the ECU to activate the blower.
How the system works? A considerable amount of generated energy is transferred to the cooling liquid. During this process, its gradual warming becomes inevitable. The liquid heats up considerably, after reaching t ° critical for the condition of the engine, the thermocouple sends a command to the electronic unit of the vehicle.
How To Test and Replace A Radiator Cooling Fan Switch
This will start the cooling process. Powerful air flows to the radiator. The coolant will return to normal at an accelerated rate.
Failure of the pump
The pump rarely fails completely, so you can only diagnose the problem after removing it. The most common problem with it is the breakage of the impeller. It is solved by replacing the pump. Other problems are deformation of the gear wheel and the pump vanes because of faults or mechanical wear and tear. This malfunction is especially serious, as it can cause the timing belt to skew. And this is its uneven wear and danger of breakage with all the unfortunate consequences for the piston group.
The reason for incorrect readings on the dashboard can be a factory defect or a large number of faults on the electrical side: from a bad connection to the ECU to the failure of the voltage regulator (“pill”). This can be indicated by uneven temperature changes (jumps), wrong readings of other devices, mismatch between the fan and the temperature readings.
This fault is less problematic: the car is not really warm, but only for the computer. But it reveals other problems, which also need to be solved.
How to check the fan switch?
The trigger sensor can be checked without removing it from the vehicle or with it dismantled. Checking the device when it is not taken off allows you to check the serviceability of the device, and the operating temperature range can be checked only after dismantling the product from the car.
- Prepare the vessel, thermometer and multimeter. Set the multimeter to ohmmeter mode.
- Place the sensor in water, warm it up to the required temperature. At a low temperature the sensor resistance is shown as infinite.
- Wait till the moment of sharp decrease of resistance. Check sensor switching temperature.
- Gradually cool the water and determine the contact opening temperature.
- Compare the readings with the passport values.
If you do not have a tester you can check the sensor on the fan switch with a test light which comes on at the moment of contact group actuation.
Dmytro Maznitsyn, the author of the video shares the secrets of testing the sensor of the fan.
In cars with carburetor engine
The sequence of checking the sensor on a car with a carburetor:
- Switch off ignition.
- Carefully remove wires from the sensor. When dismounting, keep hands and clothing away from the fan wheel as the motor can also be started with the ignition off.
- Connect wires in the plug.
- Switch on ignition. The fan should be running. If the mechanism does not start rotating, the problem is in the electric motor or wiring.
The vehicle engine may only be started with the sensor wiring terminals closed. The connected cables must be insulated against shorting to the car body.
In cars with injector engine
Procedure for checking the sensor on the injector vehicle:
- Remove the connector block from the sensor.
- Turn the ignition on. The Check Engine light on the instrument cluster may activate, indicating an error in the cooling system.
- Start the engine. After a while, the engine control unit will go into emergency mode and force the fan to run continuously.
- After coming to the service center you need to diagnose the car and remove the errors recorded in the control units.
If the fan does not turn on in emergency mode, then the problem lies in the impeller drive or wiring. The car is delivered to service by a tow-truck or a wrecker.