When starting a cold engine, the fan will turn on

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1 Topic by mastepanov2011 2017-03-04 23:02:53

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Subject: Resolved: fan goes off when ignition is turned on, won’t turn off

Good evening guys, the problem is like this when turning on.The ignition is triggered by the fan.I changed the relay to the other did not help, the fuse is intact, when you remove the chip from the fuse does not work.I think the thermostat?I read the articles, I don’t really get it.2111 8kl.Inge.

2 Response from krasnopolskaya.y 2017-03-04 23:10:38

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Re: Solutions: fan blows on ignition, does not turn off

Sensor circuit breakage. What’s behind the thermostat

3 Replies from “Robotron” 2017-03-05 08:21:17

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Re: Solution: fan blows on ignition, does not turn off

The detector itself is defective or the circuit to the sensor. It can be a good idea to clean up all of the wires to the sensor. lada2111./spravka/749-massa-2110.html

4 Reply from Patrocle 2017-03-05 14:01:31

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Re: Solved: When I turn the ignition on the fan goes off, does not turn off

Wait, how does the CARLOSON work when you remove the plug, IF it is already spinning when the ignition is turned on ??

5 Reply from mastepanov2011 2017-03-05 18:15:32

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Re: Resolved: When the ignition is turned on the fan goes off, does not turn off

I removed the plug on the ignition, it immediately turns on, but when the chip on the sensor when the ignition is on in 5 seconds, the fan does not turn off.

6 Reply from Patrocle 2017-03-06 00:18:29

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Re: Solutions: fan blows on ignition, does not turn off

Check the temperature sensor circuit for the controller (it has TWO wires),with one being the sensor for the dash. One wire goes to the ground, WP, the second to the controller O. When the ignition is on and the sensor is off there should be less than 5 volts

Why does the cooling fan turn on when the engine is cold?? Consider the causes

Timely preventive maintenance, will avoid more serious problems. If you do not pay attention and do not fix the fan, in the future, you can cause overheating of the motor. In frequent cases requires the use of an adapter for a thorough diagnosis.

By eliminating the underlying cause, you can avoid fan short circuits. Many experts believe that the process is quite easy, so every man can determine the fault of the device in his own garage. This common question torments many people who are faced with an unpleasant problem. But first we should understand the principle of the functioning of the system, which fails in stages.

It is worth noting that the fan is connected by a sensor. This important element is located in the lower part of the radiator. modern models are equipped with special triggers, which, in turn, pass through the control unit of the unit.

However, this happens in rare situations. So let’s consider another variant. Full heating of the coolant reaches at least one hundred degrees. Accordingly, there is a circuit closure, after which the fan itself turns on. In such a case, you need to look for the cause in the breakage. Since when the cooling system deteriorates, more serious problems may arise in the future.

Frequent activation of the radiator cooling fan. What could be the problem?

The antifreeze is fresh. Radiator’s perfectly clean. Radiator cap’s working.

My only hunch is that maybe the thermostat is stuck? There may be some connection to the frequent activation of the fan? Hasn’t changed the thermostat since the overhaul. Is there any connection between the heater, the heater, the heater radiator or whatever, I know it’s been a while since I had it cleaned?? Although, it seems to be blowing hot. It’s not exactly Tashkent, but it’s fine.

In general, experts who have met with this problem, please advise me where to look first disassemble? According to the information from the onboard computer, the fans turn on at 95 degrees.

It’s not a bad winter, but I don’t think it should get to the carson. Is there any cardboard between the radiators?? I have had this happen in the spring when it gets warmer and I am too lazy to take out the cardboard.к. I might still be out in the cold.

Also from the category of speculation: could someone use sealant in the cooling system? There are such sealants that fix the antifreeze leak without disassembly. The disadvantage of such sealants is that they clog the radiators and the main and the heater. Since you say “not Tashkent”. And at 95C the heater should fry pretty good.

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Contamination of the radiator

All motorists know that the radiator is at the front, and is blown by the oncoming wind. That’s why it gets all the dust and dirt on the road. Gradually this dust gathers between the radiator plates, significantly reducing the heat transfer. The airflow 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, you will first have to remove it, in some cases, it is quite possible to get to it, even without removing it from the machine. It is recommended to flush it with running water. The easiest way to do this is with a hose. In some cases, it makes sense to clean the radiator with a soft, dry brush before washing. This procedure is often combined with a radiator blowout.

Read more in the article “How to Flush the Engine Cooling Radiator”.

Why the engine cooling system fan blows on when the ignition is turned on?

The purpose of the fan in the engine cooling system is quite clear even to a person who has absolutely no knowledge about auto mechanics or work of car units. A fan is needed to cool the engine when it reaches a certain temperature.

Those more knowledgeable in automobile subjects know that the fan operation is controlled by a special sensor, which registers the temperature of the coolant in the car radiator. When the liquid is heated to a certain temperature (usually no more than 100-105 degrees Celsius), the fan turns on, which cools the radiator. In modern cars, however, the mechanism for turning on the fan is somewhat different. The sensor is not connected directly to the fan, but to the onboard computer, namely, to the computer system which controls the engine.

However, the fan only turns on when the coolant in the radiator is heated. normal operation of the system. It often happens that when the ignition is turned on, the cooling fan turns on, regardless of the engine temperature. Sometimes the fan turns on not only when the engine is hot, but also when it is cold and in winter time. Not only is the sound of the cooling fan a bit annoying in itself, but the constant operation of the cooling fan causes engine malfunction. For example, the engine becomes much more difficult to warm up, which leads to excessively rapid wear and tear of the units that are part of the car.

If the cooling fan turns on when you turn on the ignition, you should pay attention to a number of reasons that most often cause this phenomenon. If the car is equipped with an on-board computer, try doing a computer diagnostic of the car, in most cases the error codes directly indicate a malfunction.

It is worth noting that in many cars, software failures that cause an error in the cooling system causes the fan to spin all the time. In this way, the engine is protected from overheating, which leads to much more serious consequences than its long run at low temperatures.

The user said thank you:

The functioning of the fan depends on different ways, you have already seen it after reading this article. There is another reason that causes the fan to malfunction. For example, if the proper wires to the body are not screwed on properly, the fan is connected to the battery directly. It should be noted that in this case, it is necessary to take timely action to avoid serious problems.

In this case, you can expect a car fire. If a big short circuit occurs all the wires will get hot. To avoid serious consequences, it is a good idea to check the connections and wires which have access to the sensor. A secure bonding of wires and undamaged insulation, reduces the risk of serious consequences.

Not enough liquid

Very often the sensor reacts to a small amount of liquid in the system. In this case, the existing antifreeze warms up very quickly. That’s what triggers the fan. The most common cause of this malfunction is trivial negligence. Drivers often forget to control the amount of coolant. It gradually evaporates, and eventually the radiator is half-empty.

A small amount of fluid heats up very quickly and the fluid temperature is not the same as that of the engine. It turns out, the engine has just started, it has not yet heated up, and the cooling fan is already hammering, as the fluid is already hot. Solves the problem quite simply, you need to add antifreeze, and pump the cooling system to rid it of airlocks.

Radiator and A/C fan turns ON as soon as the car is turned on

The fan may also be shorted to the ground. It happens for a variety of reasons, but most often, due to a bad screwing of the appropriate wire to the body. In this case, the fan is connected directly to the battery. And it starts to work without stopping. The main problem here is the possibility of a car fire, with a stronger short circuit with more heat on the wires.

To fix it, check all the connections relating to the sensor. All wires should have undamaged insulation. They also need to be securely fastened to each other. Any small gap can cause a problem.

Many modern cars are equipped with thermostats with sensors. This allows the cooling system to be controlled more efficiently. But, such control has its disadvantages. In particular, if the system breaks down, it can start a variety of “miracles”. If the sensor installed on the thermostat fails, the fan will run continuously. The reason of it is in the following. Control unit, not getting signals about thermostat operation, goes to alarm mode. At the same time, just in case, the fan is switched on, at such error it will work all the time.

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Checking the sensor is simple enough. As any temperature sensor, in its normal state, it should show infinite resistance when the engine is cold, in all other cases it should show from 100 to 500 ohms. If there are other readings, it is better to replace the sensor. Fortunately, it is very inexpensive.

Some modern cars are completed with additional sensors of temperature of a counter flow. That is, they react to the temperature of the ambient air. If it exceeds a certain temperature, it triggers the fan. This is done to improve the efficiency of motor cooling.

This scheme is often seen in foreign cars that have sandwich radiators, consisting of 3 layers. In this case, the fan will run practically all summer, even when the engine is cold. It is not recommended to disconnect the sensor, it can lead to engine overheating.

In cars where the fan is controlled by ECU, there can be problems with contacts. They oxidize and stop transmitting signals to the control unit. It, in its turn, switches to the emergency operation mode, which is manifested by turning on the fan, as well as changing the mode of operation of other systems. In general, it is advisable to clean the contacts twice a year in the spring and fall. But if your fan suddenly starts spinning when you turn the ignition on, clean the contacts and put some special grease on them.

On some models, the air conditioner has a lot in common with the cooling system. So, a clogged air conditioner radiator makes the fan spin. This can be treated by flushing the radiator. Ideally, it is better to wash both radiators at once. It will help to make the work of this dual system as effective as possible.

For many drivers, the principle of operation of the cooling system is a dark forest. To think about how and what works there, begin only at the signs of malfunction. That’s when they start wondering why the cooling fan turns on when the engine is cold. Many inexperienced drivers are very afraid of it. In fact, it is not a very terrible breakdown, but for your own peace of mind, it is better to check the cooling system and fix the breakdown.

In the cooling system of the internal combustion engine, the fan switch sensor (FST) takes not the last place. It is responsible for engaging the fans mounted on the radiator and activated when the coolant temperature increases, and the standard cooling for the motor is clearly not enough.

If the sensor is connected directly to the ignition, but not to the relay, it is recommended to make another circuit, replacing the sensor. The sensor connected directly to the ignition, may not work properly. On some models, it is integrated with a relay, which looks much more reliable.

In this case, the scheme looks as follows:

  • Minus of the fan is connected directly from the battery, plus. from the battery through the relay (it’s also possible to connect the plus directly from the ignition);
  • The sensor is also integrated with the relay on one side, and with the mass (any part of the car body) on the other.

Obviously, if the sensor is responsible for turning on the fan on the car, the untimely activation of the system may well be due to the deterioration of the element. Let’s see what the sensor consists of.

Both fans turn on when the ignition is turned on

Its construction is not complicated. Bimetallic plate is installed in the lower part of the sensor. It is made so that when the temperature of the coolant rises, it deforms and thus acts on the contacts of the device.

  • As long as the coolant is not warmed up, the sensor plate is flat and does not move;
  • As soon as the coolant temperature increases (reaches a certain level), the plate deforms and contacts close.

It is remarkable, that on different automobile models the THB is put on this or that temperature of actuation.

There are two types of DVVs: models designed for 1 speed of rotation and models designed for 2 speeds of rotation.

When the ignition is turned on, the fan runs

As a rule, all modern automobiles are equipped with internal combustion engines with 1-speed system of switching, though 2-speed sensors are not uncommon. It will be interesting to note that on such a DVV, when a certain degree level is reached, the fan turns on at the first rotation speed. The second speed is engaged and the fan speed is correspondingly increased, in the case where the coolant temperature continues to rise.

Damage of the DVBF means not only problems when switching on the ignition, but also overheating of the engine and other unpleasant things. For this reason, first of all, if the fan starts when you turn on the ignition, you should test the functionality of the sensor.

You can test the functioning of the DVBT by yourself. To do so, suspend the sensor removed over a pan with water in it. Connect two wires beforehand with a tester (multimeter).

Attention. The metal part of the DVB should be immersed in water. In addition, the sensor should not come in direct contact with the pan.

The sensor should be triggered when the water in the pot is heated. It is advisable to study the technical data of the DVB in advance in order to correctly test the sensor. For example, some are designed to turn on after 93 degrees Celsius, others after 100 g, etc.д.

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Insufficient amount of liquid

Very often the sensor reacts to too little liquid in the system. In the process, the antifreeze that’s there heats up very quickly. That’s what triggers the fan. The most common cause of this malfunction is simple lack of attention. Drivers often forget to control the amount of coolant. It gradually evaporates, and as a result, the radiator is half-empty.

A small amount of fluid heats up very quickly, and the temperature of the fluid is not the same as that of the engine. It turns out, the engine has just started, it has not heated up, and the cooling fan is already hammering, because the fluid is already warmed up. The problem is solved quite simply, you need to add antifreeze, and pump the cooling system, to rid it of air s.

The fan can also be shorted to the common ground. This happens for various reasons, but most often due to a bad screwing of the corresponding wire to the body. In this case, the fan is connected directly to the battery. And it starts to run without stopping. The main problem here is the possibility of a car fire, with a stronger short circuit with more heat of the wires.

To fix it, check all the connections relating to the sensor. All wires must have undamaged insulation. They must also be securely fastened to each other. Any small gap can cause a problem.

Many modern cars are equipped with thermostats with sensors. It enables more efficient control of the cooling system. But, this control has its disadvantages. In particular, when the system breaks down, various “miracles” can begin. If the sensor on the thermostat fails, the fan will run continuously. The reason for this is as follows. The control unit, not getting signals about the operation of the thermostat, goes into emergency mode. In this case, just in case, the fan is turned on, with such an error it will work all the time.

Checking the sensor is simple enough. As any temperature sensor, in normal condition, it should show infinite resistance when the engine is cold, in all other cases it should show from 100 to 500 ohms. If there are other readings, it is better to replace the sensor. It costs quite inexpensively.

Some modern cars are equipped with additional counter flow temperature sensors. That is, they react to the temperature of the ambient air. If it exceeds the value prescribed in them, they give the command to turn on the fan. It is made to increase efficiency of engine cooling.

This scheme is often used in foreign cars with 3-layer sandwich radiators. In that case, practically all summer the fan will run even on a cold engine. It is not recommended to disconnect the sensor, it may cause overheating of the engine.

On cars with fan control via ECU, there can be problems with contacts. They oxidize and stop sending signals to the control unit. It, in its turn, switches to emergency mode, which is realized by fan switching on, as well as by changing the operating modes of other systems. In general, it is advisable to clean the contacts twice a year in the spring and fall. But if your fan suddenly starts spinning from the moment the ignition is turned on, clean the contacts, and coat them with special grease.

On some models, air conditioner has a lot in common with cooling system. Therefore, a clogged air conditioner radiator makes the fan spin. This can be cured by flushing the radiator. Ideally, it is better to wash both radiators at once. This will help make this dual system run as efficiently as possible.

For many drivers, the principle of operation of the cooling system is a dark forest. To think about how and what works there, start only at the signs of malfunction. That’s when they begin to wonder why the cooling fan turns on when the engine is cold. Many inexperienced drivers find this very scary. In fact, this is not a very terrible breakdown, but for your own peace of mind, it is better to check the cooling system and fix the breakdown.

Lack of liquid in the machine

The sensor partially fails at the smallest amount of liquid. Even in the presence of antifreeze, there is a momentary warming of the dachshund. This process, can disrupt the entire function of the system and cause a lot of problems. Such malfunction is characterized by trivial negligence.

With careful monitoring, you can get rid of serious problems and breakdowns. To do this, you need to check the amount of liquid. Since when it evaporates, there is no liquid in the radiator

If there is a small amount of fluid, the temperature reaches the unit’s reading. For example, if you start the engine, it will not be fully heated, but there will be instant cooling of the fan. This process happens because the liquid heats up very quickly in the unit. The problems can be solved in the simplest way. By adding a little antifreeze, you can avoid airlocks in the system.

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