Home Article Engine temperature does not drop the fan works

Engine temperature does not drop the fan works

The reasons for the frequent inclusion of the cooling fan

Why is the cooling fan constantly working or often turns on? After all, this is evidence of the poor operation of the cooling system. This can lead to overheating of the motor and its failure. This problem is quite serious, in some cases, to eliminate, you will even have to partially disassemble the engine. The coordinated operation of the power unit depends on how quickly you identify the malfunction. For verification and repair, no special skills are required, any person will cope with this. The main thing is to know how to search for the causes of such behavior of the cooling system.

Why the cooling fan is constantly working or often turns on, it becomes clear from the principle of its action. It turns on the sensor located at the bottom of the cooling radiator. This sensor responds to an increase in the temperature of the coolant, as a result, the fan turns on. It creates an additional flow of air, which enhances fluid cooling in the radiator and, accordingly, the motor itself. Based on this, it becomes clear that the fan is constantly working, only on overheating power units. To avoid engine failure, it is necessary to react in a timely manner to the problem and eliminate it.

The engine overheating often occurs due to the jamming of this element. The fan reacts to this, in the case of jamming the thermostat by half an open. At the same time, the movement of fluid through the system slows down, which causes a decrease in the efficiency of heat removal. As a result, the motor begins to overheat, respectively, the temperature of the coolant increases. The fan switch reacts to this. As a result, he works constantly.

Checking the thermostat is performed quite simply. To do this, the engine is started, and warm it up to the temperature of the thermostat valve. This indicator is indicated on the case of the thermostat itself. We are waiting a little more, and check the temperature of the upper and lower pipes. If both pipe are evenly hot, then the cause of the constantly operating fan was found. For more confidence, carefully inspect the thermostat valve after removing the part from the engine. Eliminate the malfunction by replacing the thermostat with a working spare part.

In many cases, the cause of the coolant temperature in the radiator becomes poor water pump operation. In this case, the antifreeze is slowly passing through the system and heats up too much. Getting into the radiator, he does not have time to cool to normal temperature, and goes through the next circle, heated even more. If the pump is working at the very least, then such a problem is expressed, only the constant operation of the fan. If the pump completely refused, then in a matter of minutes the car will “boil”. This is an extremely dangerous condition that almost always leaves behind the consequences in the form of problems with the engine.

Usually a water pump does not fail suddenly. First he gives signals about his malfunction. The first alarming signal is an increase in the operation frequency of the radiator fan. The main reason for the refusal is the destruction and jamming of the bearing. Therefore, a manifestation of a breakdown can be a hood from under the hood or a knock that is clearly audible when working at idle. Often the knock of the pump is taken as a malfunction of the camshaft. The breakdown is eliminated by replacing the pump, in some models it is possible to replace only the front of the pump along with the bearing.

Quite often overheating causes congestion in the cooling system. This problem is often quite difficult to identify. Therefore, at the first signs of increasing the inclusion of the fan for no special reason, you should first rinse the system. In many cases, this is enough. Also, just in case, you can blow the radiator.

engine, temperature, does, works

Usually cleaning the radiator and cooling channels is carried out in conjunction with the replacement of antifreeze. For washing, pour the coolant. After that, a strong solution of citric acid or water with special additives is poured. After they give the car for half an hour to work. The spent cleaning agent is drained, and fresh antifreeze is poured. In most cases, such a procedure helps guaranteed to eliminate pollution in the cooling system.

All motorists know that the radiator is located in front, and is blown by the oncoming wind. Therefore, it is he who gets all the dust and dirt that falls on the road. Gradually, this dust is collected between the radiator plates, significantly worsening heat transfer. Air flows, in this case, cool the liquid much worse. It gradually heats up to a high level, and causes the fan.

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 rinse it using running water. The easiest way to use the hose for this. In some cases, it makes sense to clean the radiator with a soft, dry brush before washing. Often this procedure is combined with blowing a radiator.

It’s no secret that the cause of excessive fluid heating is air traffic jams. They appear due to errors when replacing antifreeze, as well as due to leaks in the cooling system. As a result, the liquid warms up unevenly, which leads to unstable operation of the fan, with frequent inclusions when the radiator of the hotter fluid is entered into the radiator.

Before elimination, it is necessary to check the system for fluid leaks. Eliminating them, go to the passage of traffic jams. For this you will need a compressor. Unscrew from the throttle one of the tubes supplying the coolant to it. Next, you need to connect the compressor to the neck of the expansion tank, and serve compressed air into it. Usually a couple of minutes enough to drive out all the plugs available.

Warming for the winter. Many motorists put special heater 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 quite high. In the presence of insulation, the engine is not enough, which makes the fan work more intensively. To eliminate the reason, just remove insulation from the radiator.

The car cooling system should always be in good condition. Therefore, the driver needs to carefully monitor the state of this system. It is especially important to correctly find the reason why the cooling fan is constantly working or often turns on. This is certainly not a fatal problem, but neglect of this signal can lead to serious engine faults.

The fan works on a cold motor: causes, diagnosis, repair

To begin with, the indicated problem can clearly indicate both the malfunction of the liquid cooling system and the fault of the fan itself. In any case, we are talking about a breakdown that cannot be ignored, since the risk of ICE overheating significantly increases significantly.

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For a better understanding, it is necessary to superficially consider the principle of operation of the fan on most modern cars. Blowing is turned on by means of a special sensor, which is located at the bottom of the radiator. Also, many cars use a separate engine control unit of engine cooling. There are still models in which the ECU itself is responsible for the inclusion of the fan, but this design is rarely used.

So, after heating the coolant to the temperature, on average, about 100 degrees Celsius, the sensor or the control unit closes the electric circuit. After that, the fan turns on, improving the cooling of the motor. Когда температура ОЖ понижается до необходимого показателя, происходит размыкание цепи и обдув прекращается.

How to Diagnose A Constantly Running Fan

As you can see, on a cold engine, the fan should not work. So, in order to determine why the fan is early turning on, it is recommended to start starting with a computer diagnosis of the car with a diagnostic connector of OBD II. The fact is that the ability to consider error codes from the ECU allows you to more accurately determine the cause of the malfunction.

We also note that in cases where the control unit fixes the errors of the cooling system, the fan can spin immediately after the ignition is turned on even on a cold ICE. This feature is found only on some models and is, in fact, protection against overheating of the power unit, since the constantly working fan reduces the temperature.

After the repair in this case, it will also be necessary to discharge errors. To erase an error from the ECU, on some models it is enough to remove the terminal from the battery for a couple of minutes, while at the same time, the other reset is carried out using diagnostic equipment.

Common problems of the cooling fan

Now let’s look at the frequent problems that are associated with the cooling system and the fan itself.

  • First of all, in many cases, the contact sensor of the air system is closed. In this case, blowing triggers immediately after the ignition is turned on.

In the process of diagnosis, on a cold sensor, the resistance is measured on the output using a multimeter. Deviations from the norm will indicate the need to replace the element.

engine, temperature, does, works
  • The liquid system is not enough coolant. In this case, the fan operation occurs due to the fact that a small amount of antifreeze or antifreeze heats up very quickly. In other words, the fan is working and starts naturally.

As a rule, leaks or a decrease in the level of coolant in an expansion tank are the main reason. Please note that antifreeze is a mixture of concentrate and water. Water gradually evaporates from the system, as a result, the level decreases. For this reason, it is recommended to periodically carry out control and topping of the liquid on special marks.

If there is little coolant in the system, heating occurs quickly. It is also noteworthy that the real temperature of the fluid is very different from the temperature of the internal combustion engine. It often happens that the cold engine has been launched, the temperature arrow has not yet risen on the dashboard, and the fan is already triggered due to too hot liquid. To solve the problem, it will be enough to pour antifreeze, remove air traffic jams from the cooling system.

The fan in this case can close the battery and work non.stop. In such a situation, you need to check all the contacts, wiring and other elements. The wires should be reliably insulated and properly connected.

  • The fan sensor failed, which is integrated into the thermostat case. Quite a lot of modern machines constructively have a thermostat, which is combined with a fan control sensor.

Such a solution allows you to implement flexible control of the engine cooling system. However, in the event of a temperature sensor malfunction in the thermostat case, the fan can start working without disconnecting. The fact is that the control unit begins to receive incorrect signals about how the thermostat works. As a result, the emergency mode is involved, the fan turns on and works constantly.

In such a situation, you need to check the sensor with a multimeter. Normally, on a cold engine, its resistance is endless, in other cases, the indicator should be 100. 500 Ohms. Deviations in the indications from the norm will indicate that the sensor needs to be changed for a new or obviously working.

  • Outdoor temperature sensor failed. Such a problem is found on some cars that are equipped with ambient temperature sensors. If the temperature is higher than the permissible limit, then these sensors use the fan.

This solution allows you to more effectively cool the power unit, especially on cars that have a powerful forced ICE and several radiators. On such units, the fan can be turned on in the warm season even on a cold ICE to protect against engine overheating.

If we talk about malfunctions, in most modern cars, the cooling system is closely related to the climatic installation. It is for this reason that the air conditioning radiator is polluted that the engine cooling fan will work constantly at maximum speeds.

To solve the problem, external cleaning of the air conditioning radiator and radiator of the cooling system may be required. The fact is that these radiators stand next to each other, dirt, dust and fluff are stuffing between them. Removing such a “fur coat” allows us to normalize the operation of the air conditioning and cooling system, get rid of frequent fan on and increased noise during it.

Cunnered radiator

Dirty radiator is one of the reasons why the VAZ 2121 Chevrolet engine can be warming up. Frequent trips through mud, overcoming water fords and riding along gravel gradually clogs the honeycomb with various particles. Since the honeycombs are now not blown, the effectiveness of the radiator is reduced, therefore, NIVA begins to overheat not only in traffic jams, but also in motion.

The serviceability of the fans and other parts of the cooling system will not help. The motor will be bask. In addition, the effectiveness of the air conditioner is reduced, since its condenser is also covered with dirt. To solve this problem, it is necessary to rinse both radiators using foam and a washing of high pressure.

It is worth noting that with a dirty radiator, overheating is not always observed. A slight overestimation of the engine operating temperature is possible. Therefore, at the first symptoms, it is better to call on the sink.

Break of a drive belt

In addition to electromechanical damage, a banal breakdown of the belt is possible. Which will also cause overheating of the engine causes and methods of elimination involve its replacement. Therefore, on the road you must have a spare fan drive belt.

If the road cannot be eliminated in the road with a fan drive. The movement can still continue. Stop periodically. Engage the engine to cool. In this case, it is required to turn on the fan of the cabin heater for the entire power. The temperature of the cabin of the cabin should be set on the maximum. The stove helps to cool the engine and increase its heating time.

Why the car is warming up?

There are several reasons why the engine of your car overheats with the air conditioner on. Here are the most likely reasons:

  • The ineffective functioning of the cooling system is one of the most common reasons that lead to overheating of the motor. So, overheating of the engine can be due to leakage of coolant in a radiator, in an expansion tank, in a pipe, in the stove. In this case, when depressing the system, you need to constantly add antifreeze or water into the cooling system (unless, of course, damage to the engine cooling system is not critical). Also, the cause of overheating of the motor may be an old coolant. For example, if you have not changed antifreeze for 2-3 years, then its properties will be lost. In this case, it is better to replace the old coolant with a new. Including inspect the radiator. If you see a lot of dried dirt or garbage on it, this can also be the cause of engine overheating. In this case, it is necessary to rinse the radiator, directing the hose to the sink to its ribs. Please note that when flushing the radiator, the water pressure in the hose should not be maximum. Otherwise, you risk, bending the radiator, to disable it. If there are too many damaged cells on the surface of the radiator or you found a rust, then it’s time to buy a new radiator.
  • Very often, the car overheats when you move at low speeds or when operating the engine at idle (for example, when you stand in the heat in place for a long time) with the air conditioner on. This may be due to the lack of air flow through the radiator. But this does not say that the radiator is clogged. After all, the car is standing and the air flows cannot pass through it. When the machine is at idle, then the engine cooling fan automatically turns on, which helps the engine to stay within the operating temperature. As a result, if your car constantly starts to warm up at idle (especially when the air conditioner is turned on), then, quite possibly, the cooling fan, or its relay, or the coupling, failed.
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) Dirty radiator

If your car has traveled more than 80 thousand. km, most likely the cooling radiator in it is very contaminated, which can also cause engine overheating.

In order to avoid this, it is necessary to flush the radiator every year. It is desirable that along with cleaning the radiator to change and the cooling liquid itself. Despite the fact that the manufacturer himself recommend changing antifreeze every 3 years, for our part, we strongly recommend changing this coolant better every year.

How To Test and Replace A Radiator Cooling Fan Switch

In conclusion, dear readers, we would like to once again remind all motorists that, in addition to regular verification of the entire cooling system (especially before a long trip), it is necessary to periodically conduct a full diagnosis of the work of all the most important car systems. Do not forget to regularly check the oil level in the car engine. Remember that maintaining the oil level in the engine at optimal values, you reduce the load on the engine itself and thereby prevent excessive (heating) of the engine.

The less the load on the engine, the greater the service life of the power unit of the car. Good luck friends!

Engine overheating: main features and causes

Let’s start with the signs. First of all, this is an indicator of the engine temperature on the dashboard in the red zone. Also, some models can simply light up a signal lamp indicating overheating.

Another sign of overheating of the motor is to reduce engine power, traction loss and detonation knocking with a sharp press on the gas pedal, or just when accelerating. The reason- the process of combustion of fuel in the cylinders (explosions of the working mixture instead of combustion) is impaired from increasing temperature.

We go further. It is important to understand that the normal operating temperature of the engine is an indicator of 85-95 degrees Celsius. Also acceptable is the engine temperature up to 100 degrees or even 105, especially if such growth is short.term (up to 5 minutes). With this situation, drivers often face a simple in traffic in the heat.

However, if the motor heating is above 105 degrees, then it is already overheating and you need to look for the reasons. The simplest and most understandable is the low level of coolant in the cooling system. We also add that the liquid in the engine boils at a low level, since the surface of the contact of the liquid and the heated motor is insufficient, that is, heat removal is disturbed.

  • It should also be borne in mind that the cooling system is not completely sealed and closed. During operation, the fluid is evaporated, which is the cause of a decrease in the level.

Often a radiator, nozzles and places of joints begin to flow. Internal leaks should not yet be excluded when, through cracks in the BC or HBC, as well as through the penetrated gasket of coolants, it goes into the cylinders.

  • It is important to check the condition of the radiator. Radiator honeycombs are small, often the radiator is polluted outside. There may also be a violated circulation of coolant inside the radiator due to the accumulation of deposits. In this case, when the engine cooling fan turns on, the cold engine radiator may indicate problems with liquid circulation.

By the way, deposits on the walls of the engine and inside the radiator often occur after using low.quality coolant or, worse, water. In the first case, cheap antifreeze or antifreeze does not protect parts from corrosion, has no detergents, etc.D. In the second, in the water itself there is the presence of impurities and salts. It is recommended to thoroughly rinse the radiator of the car from rust, as well as clean the entire system.

  • In many cases, the radiator electric fan is triggered at the signal of the sensor. If the sensor does not give a signal, the fan will not work or can work with insufficient performance.
  • Air traffic jams may well form in the cooling system. It is noteworthy that the temperature sensor may not show overheating. In any case, the air cork needs to be “expelled”, which will exclude the presence of air.
  • Another reason that the engine is boiling, the radiator is cold and the cooling fan is constantly working, is the thermostat. In a nutshell, the thermostat is a valve, which divides the cooling system into two circles, through which the coolant circulates. A small circle involves circulation only along the cooling shirt for quick heating, and a large liquid allows the liquid to go through the radiator for improved cooling.

However, if the thermostat is wedges, then the coolant can circulate only in a small circle, that is, the radiator is cold, but the engine overheats. To accurately determine, just feel the lower nozzles going to the radiator. Cold nozzles with a overheating motor are a sign of problems with the thermostat.

  • Completes the list of main breakdowns of the pump (water pump water pump). The specified pump forcibly pumps the coolant on the system to achieve better circulation.

As a rule, the pump either starts leak or its impeller wears out. Less commonly, the pump jams. In the case of a cold radiator, provided that the pump leak is absent, it is appropriate to talk about the wear of the impeller. In simple words, the pump pumps the liquid poorly, the coolant in the engine (small circle) heats up much faster than in the radiator itself. It turns out that heating is uneven, the radiator is cold, and the engine boils. Recall once again, similar symptoms occur in the case of air plugs.

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The temperature arrow jumps with a working thermostat and dtozh

In some cases, it happens that the thermostat is working, as well as the temperature sensor and wiring. In this case, the temperature arrow jumps arbitrarily, overestimating or underestimating the indications, in the arbitrary range.

Often the problem is in the electronic board of the instrument panel. If the soldering of such a fee is of poor quality, after a few years problems arise. The malfunction can be eliminated by parsing the shield and rolling. Within the framework of such works, special attention should be paid to resistors and output mass. If you plan to perform work with your own hands, you need to have a small power soldering iron with a thin rod.

We also note that the shooter with other working elements of both the mechanical and electric part can jump if the engine cooling the engine is dumbfounded. In other words, the air in the cooling system forms an air cork. Such a traffic jam is much faster and stronger than antifreeze or antifreeze.

As a result, the sensor responds to a change in temperature, the indicator arrow randomly changes the position. At the same time, the air in the system indirectly indicates that the liquid leaks from under the cover of the expansion tank, a decrease in the level in the tank, etc.D.

Common malfunctions

Since the fan is spinning, it must be forced to stop and turn on only when there is a real need for this.

There are several main reasons why the fans of the cooling system on the cold engine may turn on. This is due to:

  • inclusion sensor;
  • cooling liquid;
  • mass;
  • thermostat;
  • temperature sensor;
  • contacts;
  • air conditioning.

Each of the points may cause why, with a cold engine, the fan works and begins to rotate.

The inclusion sensor

One of the most common reasons why the fan works on a cold engine is the closure of the controller, that is, the sensor.

Quite often it happens that the fan starts along with the ignition of. If this occurs at the same time, there probably was a closure of contacts on the controller. As a result, blowing is constantly working.

Although the breakdown is the most common, it is the most harmless and safe. The most poor consequence of such a phenomenon is the complete category of the battery. This will happen if you temporarily leave the ignition on.

To check whether the closure is to blame or not, it will be necessary to check the resistance using the multimeter by applying the probes to the conclusions. When the sensor is working, the multimeter shows endless resistance, that is, it displays the corresponding value on the display.

If you see that the resistance is less, then the contacts probably closed. You will need to replace the controller. Such a malfunction is displayed by a separate code during computer diagnostics.

Cooling liquid

Sometimes there is no need to look for all kinds of reasons why suddenly a cooling fan on a cold engine turns on. Experienced motorists advise starting with a banal coolant test.

The thing is that quite often the sensor reacts by activating the fan to the coolant deficiency in the system. The amount of antifreeze that is available is too quickly heats up, which leads to the launch of the fan with a cold motor.

Therefore, not so rarely the cause of such a malfunction is the banal inattention of the car owner. Some drivers simply forget that it is necessary to control the fluid level and periodically add fresh antifreeze into an expansion tank. It will gradually evaporate, because the stocks must be replenished. With a half.empty radiator, the sensor really begins to respond accordingly. To cool the motor, it will connect air cooling into operation, sold using a fan.

Due to the shortage of the cooling fluid, its heating occurs faster than with a completely filled system. And the indicators of the coolant temperature do not coincide with the temperature of the engine. As a result, it turns out that the motor was just launched, it has not yet warmed up, and the fan already rotates its blades in full due to the high temperature of rapidly heated fluid.

Solving the problem is extremely simple. Share the missing amount of antifreeze in the expansion tank. Also, the system may be pumped additionally if air traffic jams have formed inside it.


Another potential culprit in the emergence of such a situation with the fan of the cooling system is the closure to the mass.

There are a lot of reasons for such a phenomenon. But often this is explained by the fact that the wire of the mass was simply poorly screwed to the car body. Because of this, the fan is directly connected to the battery, which provokes its constant rotation.

engine, temperature, does, works

The situation seems banal, but the consequences of such a shortage are quite serious. Cars can simply light up. This is possible with a strong circuit and overheating of the wiring.

To eliminate the malfunction, it is necessary to check all the connections related to the sensor at the bottom of the radiator. Make sure the integrity of all wires and the presence of high.quality isolation on them. Also firmly combine the wiring. If necessary, use an additional insulation layer, or replace the wires in case of severe wear or damage completely.

engine, temperature, does, works

Problems with the thermostat

There are thermostats supplemented by sensors on modern vehicles. Such a combination of devices makes it possible to increase the efficiency of control of the engine cooling system. But this solution also has some weaknesses.

Periodically, the thermostat sensor stops working, which is why the fan of the air cooling system begins to constantly rotate. The reason for this phenomenon is extremely simple. The ECU does not receive any signals from the thermostat, since a special sensor is responsible for them. As a result, electronics transfer it to work in the conditions of emergency mode. For reinsurance, the ECU launches the fan to prevent engine overheating. If such a malfunction occurs, the fan will spin until its performance is returned to the sensor.

Checking the sensor should not cause any special problems in the car owner. This is actually a regular temperature controller. With good condition, it shows endless resistance when the engine is cold. In other cases, the resistance parameters are 100-500 Ohms. If a multimeter check shows deviations from these indicators, you need to replace the controller. This is a fairly cheap consumable, so spending a lot of money on repairs will not have to.

Additional sensor

Here we are talking about the air temperature sensor. It is used on some cars as an additional controller that regulates the temperature indicators of oncoming air flows. In fact, this device controls and reports the air temperature from the environment, which enters the air ducts outside the car.



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