How to connect the cooling fan relay

“Borey-K”, “Borey-KV”. a unit of smooth control of the car radiator fan (BU EVSO) with switching on the “minus” wire

The design uses a two-pin sensor that, depending on the temperature, feeds the motor directly or through resistors; a combination of parallel and series connection. The fan disperses heat by forcing the necessary airflow through the radiator, which removes the heat to the atmosphere.


The fan continues to work briefly even after switching off the ignition. If the vehicle design does not provide a fan relay, for forced cooling of the radiator will have to install it yourself. So armed with the schematics of the wiring blocks of hh which should be on the car How to connect the cooling fan through the button in the cabin In the 3-wire fans are added tacho output. But it also has disadvantages. To solve this problem, you need to periodically turn on the fan for an amount of time that allows you to get a few reliable tacho cycles. To get low speeds the voltage is reduced, to get high speeds the voltage is increased. Revision of the circuit of the electric fan motor Many responsible motorists can disappear for hours in the garage, trying not only to eliminate the problems that have appeared, but also to prevent the occurrence of new malfunctions by various improvements and refinements. To begin with let’s change the terminals on 2 pin chip connected to the cooling fan.

connect, cooling, relay

How the cooling system fan turns on

electric fan relay; 5. electric oil pump relay; 6. main relay (ignition relay).

Note: the order of relays and fuses can be arbitrary, we are guided by the color of wires. So we find the relay, from which go a thin pink wire with a black stripe, coming from the main relay (pin 85) (not to be confused with the thin, red wire with a black stripe, coming from the controller) and a thick white power wire with a black stripe (pin 87) (white and pink wire we need), this is the fan relay.

How to connect the relay on the fan

In order to save money and simplify the design a simplified circuit of the cooling system fan switch is used on cars. Circuit includes fan motor, fuse, temperature sensor, and connecting wires. The electric motor is connected to the ground and also to the battery plus via a fuse. Temperature sensor is included in the ground wire gap.

This scheme is good for its simplicity, there is no need to use expensive elements, and the number of wires is minimal. But it also has disadvantages. For example, the temperature sensor, which acts as a switch, carries a lot of current, which affects its service life. And another disadvantage. this is a sharp turn on of the motor. Load on the engine rises sharply to the maximum value, and it negatively affects the condition of the electric motor.

The radiator cooling fan is one of the key elements that save the motor from possible overheating. It should turn on when the coolant has too high a temperature and is not sufficiently cooled when flowing through the radiator. A sensor is responsible for switching the cooling fan on/off.

The thing is that quite often the sensor reacts by activating the fan to the lack of coolant in the system. The amount of antifreeze that is available heats up too quickly, which causes the fan to start when the motor is still cold.

The use of semiconductors

A thyristor switch or a field-effect transistor design can be used instead of an electromagnetic relay. The essence is the same, but there are no mobile contacts, their function is performed by electrons and holes in the semiconductor crystal. But don’t forget about thyristors and transistors cooling, install heat sinks that will be able to provide the necessary heat dissipation.

Soft-start is a very useful function for engine control. Such an innovation provides a gradual increase in the load on the motor. This is accomplished by using PWM modulation. But along with all the innovations, you can use the second temperature sensor in the cooling system, which has a temperature response of 5 degrees less than the main.

If the main sensor triggers, the fan turns on at full power, when the second sensor triggers, its speed should be half as much. This requires the use of a resistor in the wiring. The one installed on the heater fan is perfect. This prevents the temperature in the system from rising to extreme values.

On the cooling fan radiator VAZ 2114 depends engine performance when driving in hot weather, with a load and, especially, in traffic jams. Sometimes the thermostat of the fan does not work and the motor overheats.

It is difficult to eliminate such breakage on site, so it is better to install the button of forced fan switching on beforehand, with the help of which you can switch on cooling of the radiator, if necessary, to prevent engine overheating.

Using semiconductors

Therefore, armed with wiring diagrams of the wiring harness, which should be on the car As the gauge is used a resistive temperature sensor. Here are such useful little things to add to your car, so that the failure of the VAZ fan sensor does not catch you unawares. Also it can rotate at different speeds with different operating modes of the power unit of the car. To do this simply remove the wire harness from the clamps placed on the housing. Wiring diagram for a 12 volt fan.

Connect power wires to battery with wire cross section at least equal to that of fans wires. First: Get hold of some imported three-output fan switch: see the diagram in the fig. In the second case, the lighting and the exhaust system work in parallel. To do this, simply remove the wiring harness from the catches placed on the hood. Today we will consider the reasons why the VAZ fan does not turn on in automatic mode, replacement of the temperature sensor, as well as make a small scheme of forced start blowing. This heat must be silently and effectively removed from the system. The cooling system fan does not turn on. What is the reason.

Use of electromagnetic relay

To drive the fan, a DC motor with permanent magnet excitation ME or similar is installed.

It is also not recommended to connect the circuit so that after switching on the ignition the electric fan is constantly rotating, as this significantly reduces its life. Installation and connection of the fan Given that cars are equipped with fans in standard mode, re-installation may be necessary only in the course of repair work, that is, after replacing the broken parts of the old part or when installing a new device.

Then using the same wrench, unscrew the bolts fixing the radiator tube, which connects it to the air conditioning system if, of course, this is provided by the design of the car and displace it to the side. I put the relay on pin 30 of the circuit. Nevertheless, only in recent years technology of fan control has developed significantly. We also advise not to connect the circuit so that after switching on the ignition, the electric fan is constantly rotating, as this significantly reduces its life. Source fornk. It is convenient to place the relay on the side surface of the body behind the right lamp, closer to the battery.

The relay circuit of switching on the fan of the cooling system of a car

To implement a cooling system fan switching circuit, there are many schemes, consider one of them, which has proven to be most effective. Working principle is to turn on the fan, which cools the engine when it reaches a certain temperature.

As a result, the device will be a relay with a control system switching relay when the engine reaches a certain temperature. Principle scheme is based on commutator 130 from ignition system of GAZ car, you can not use the commutator 131 from later models this scheme is not valid for it. You can buy the 130th commutator in any auto store, it’s not scarce, so you can easily get it.

The weakest point of this switch is transistor KT848, the power transistor is located on the radiator. If the element is broken it is most likely this transistor.

So, on the basis of this commutator we make the circuit shown in the following figure.

The principle is simple, with increasing temperature the voltage level on the sensor decreases. It is clear that almost all voltages go to trimmer resistor R, the moment the voltage across the trimmer resistor becomes less than the stabilization voltage of Zeneron V the transistor will close, which in turn will cause the opening of transistors V5 and V6.

Thus the control contacts of relay PC503 will be energized (see Fig.3). the third figure), it will switch over and the fan will start to rotate. Important role in the circuit is played by the resistor R3 its nominal value determines the value of the motor temperature at which the fan will turn off.

The smaller is the value of resistor R3, the bigger is the temperature difference between turning on and off the fan. In other words if you decrease the value of resistor R3 the motor will have to cool for longer time.

To avoid failure of the relay resistor R3 should not be less than 50 kOhm, generally its value ranges from 50 kOhm to 1 Mohm. Resistor R is a finer tool for adjusting the switching temperature of the relay, with which you can adjust the switching temperature with an accuracy of 1 degree. General wiring diagram of the circuit, relay, power, temperature sensor is shown below.

The device will be in an aggressive environment subject to vibration and temperature, so the initial setting for a certain temperature will eventually go by 2-3 degrees. Otherwise, the circuit performed very well.

How the fan turns on?

The device works differently depending on the model of the car. in the carburettor engine there is a sensor for switching on the fan, which sends a signal to the relay when the liquid heats up to a preset temperature (100-105 ۫). Then the fan relay is activated and energizes the electric motor. The injector engine is controlled by an electronic unit, which first analyzes the information received by the controller and then transmits to the relay.

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