As you know, various malfunctions of the engine cooling system do not allow the engine to reach the optimal temperature regime. The engine may overheat, which can lead to its rapid breakdown, or stay cold, i.e. do not exceed the operating temperature.
Modern cars use a combined internal combustion engine cooling system: liquid and air cooling. By liquid should be understood the circulation of antifreeze or antifreeze through special channels in the cylinder block and the head of the engine cylinder block.
The coolant circulates thanks to the pump (pumps). For additional cooling, the coolant can also circulate in a small circle (inside the engine) and in a large circle, that is, through the radiator.
Air cooling is implemented using a fan, which removes excess heat by supplying air flow into the underhood space for blowing the motor. The specified fan is activated in that case, when the heating of the unit is high enough.
However, quite often drivers are faced with a question, why does the cooling fan turn on when the engine is cold, the engine fan starts in winter or spins constantly. In this article we will talk about that, for what reasons does the cooling fan start on a cold engine, the engine cooling fan does not turn off or the specified fan does not work correctly.
The fan works on a cold engine: reasons, diagnosis, repair
Let's start with that, that the specified problem can clearly indicate a malfunction of the liquid cooling system, as well as for problems with the fan itself. In any case, we are talking about a breakdown, which cannot be ignored, as the risk of overheating of the internal combustion engine increases significantly.
For a better understanding, it is necessary to superficially consider the principle of operation of the fan on most modern cars. Blowing is activated using a special sensor, which is located in the lower part of the radiator. Also, many cars use a separate engine cooling fan control unit. There are still models, in which the ECU itself is responsible for turning on the fan, however, this construction is rarely used.
so, after heating the coolant to temperature, in the middle, close 100 degrees Celsius, the sensor or control unit closes the electrical circuit. After that, the fan is turned on, improving engine cooling. When the coolant temperature drops to the required level, the circuit opens and the blowing stops.
As you can see, the fan should not work on a cold engine. so, to determine, why does the fan turn on early, for injection cars with an OBD II diagnostic connector, it is recommended to start with computer diagnostics of the car. The point is, that the ability to read error codes from the ECU allows you to more accurately determine the cause of the malfunction.
We will note still, that in cases, when the control unit detects cooling system errors, the fan can rotate immediately after turning on the ignition even on a cold internal combustion engine. This feature is found only on some models, essentially, protection against overheating of the power unit, as a constantly running fan lowers the temperature.
After repair, in this case, you will also need to reset errors. To erase the error from the ECU, on some models, it is enough to remove the terminal from the battery for a couple of minutes, at the same time, others are reset using diagnostic equipment.
Common cooling fan problems
Now let's look at common problems, which are related to the cooling system and the fan itself.
- First of all, in many cases, the contacts of the air system sensor are shorted. In this case, the blowing is triggered immediately after the ignition is turned on.
In the process of diagnostics, the resistance at the outputs is measured using a multimeter on a cold sensor. Deviations from the norm will indicate the need to replace the element.
- There is not enough coolant in the liquid system. In this case, the fan is triggered because of that, that a small amount of antifreeze or antifreeze heats up very quickly. In other words, the fan is working and starts naturally.
Usually, leakage or a decrease in the coolant level in the expansion tank is the main reason. pay attention, 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 control and top up the liquid according to special matyuks.
If there is not enough coolant in the system, heating happens quickly. That is also remarkable, that the actual temperature of the liquid is very different from the temperature of the internal combustion engine. This is often the case, that the cold engine was started, the temperature needle on the dashboard has not yet risen, and the fan is already activated due to too hot liquid. To solve the problem, it will be enough to pour antifreeze, remove air plugs from the cooling system.
- The fan is shorted to ground, since the wire may not be screwed securely enough, there was destruction of the contact point, etc.
In this case, the fan can close to the battery and work continuously. In a similar situation, you need to check all contacts, wiring and other elements. Wires must be securely insulated and properly connected.
- Fan sensor failed, which is integrated into the thermostat housing. Quite a lot of modern cars have a thermostat by design, which is combined with the fan control sensor.
Such a solution allows for flexible control of the engine cooling system. However, in the event of problems with the temperature sensor in the thermostat housing, the fan may start to work without shutting down. The point is, that the control unit begins to receive incorrect signals that, how does a thermostat work. As a result, the emergency mode is activated, the fan turns on and runs continuously.
In such a situation, you need to check the sensor with a multimeter. Normally, on a cold engine, its resistance is infinite, in other cases, the indicator should be 100 — 500 Ohm. Deviations in readings from the norm will indicate that, that the sensor must be replaced with a new or working one.
- The outside air temperature sensor has failed. This problem occurs on some cars, which are equipped with ambient air temperature sensors. If the temperature is above the permissible limit, then the specified sensors will activate the fan.
This solution allows more efficient cooling of the power unit, especially on cars, which have a powerful forced internal combustion engine and several radiators. On such units, the fan can be turned on in the warm season even on a cold internal combustion engine to protect the engine from overheating.
- After starting the air conditioner in the car, the fan is constantly running. Note, on some models, such operation of the fan is normal.
If we talk about malfunctions, on most modern cars, the cooling system is closely related to the climate control system. It is for this reason that contamination of the radiator of the air conditioner can lead to, that the internal combustion engine cooling fan will work constantly at maximum speed.
To solve the problem, external cleaning of the radiator of the air conditioner and the radiator of the cooling system may be required. The point is, that these radiators are next to each other, dirt is packed between them, dust and fluff. Removing such a "fur coat" allows you to normalize the operation of the air conditioning and engine cooling system, get rid of frequent fan activations and increased noise during its operation.
- Problems with wiring and electrical contacts. Regardless, how fan control is implemented, contacts are a frequent cause of problems.
Oxidation of the contacts or damage to the wiring, insufficient fixation in the places of connections and other defects lead to short circuits, transmission of incorrect signals to control units, etc. As a result, the mode of protection against overheating is turned on with the help of constant rotation of the fan, etc.
In order to avoid such a situation, experienced drivers recommend cleaning the contacts before the onset of winter and summer for preventive purposes. Processing with special lubricants and protective compounds is also actively practiced.
As a result
As you can see, The internal combustion engine itself and its systems require regular maintenance. As for the cooling system, it is also no exception and requires increased attention.
We also recommend reading the article about it, what are the most frequent malfunctions characteristic of the car engine cooling system. From this article, you will learn about the basic reasons for incorrect operation and possible breakdowns of the specified system.
If the driver noticed, that the cooling fan started working at maximum speed all the time or stopped turning off in a timely manner, then you should first check the level of antifreeze, pump and thermostat performance.
It must also be taken into account, that the reason for such operation of the fan may be the clogging of the cooling radiator or the temperature of the outside air being too high, closing contacts, etc. Don't forget about that, that the fan can constantly rotate on a cold engine with the air conditioner running.