In fact, not many drivers are familiar with this mode and know about its useful and negative sides.

Air recirculation in a car is the intake and “distillation” of air masses directly from. In this case, the air is cooled, passing through the air conditioner, and after passing through it is distributed through the air nozzles for supply to the passenger compartment.

pros

When using this mode, the air temperature in the cabin is lowered in faster lines than the mode of intake of air masses from the environment. This is mainly due to the repeated passage of air in the car, the temperature of which is already lower than the environment, through the air conditioner.

With the reverse procedure - heating, it is still easier, since the temperature in the cabin is much higher than outside the car.

Another positive point is the fact that the power consumption for the operation of the compressor is much lower than when taken from outside.

Recirculation is also an indispensable mode for people sensitive to road dust, pollen, unpleasant odors and other allergenic factors.

As an example, it is worth mentioning a situation that is probably familiar to any driver - this is a KAMAZ walking in front of you or any other car that emits strong specific odors, recycling in this case is an excellent way out.

Minuses

One very important point should be attributed to the negative factors of air recirculation - this is the absence of any air exchange. In simple words, you have to breathe the same air.

With prolonged use, fogging of the windows is inevitable due to an increase in humidity in the passenger compartment. Many solve this problem by joint and recycling mode.

Where is the power button

The location of the recirculation button varies depending on the model of your car, but there are two generally accepted symbols (icons) that will make it easy to find them.

The buttons look like this:

These designations are typical, unfortunately, not for all models. For example, on VAZs, the recirculation button looks like a circle of three lines and is located to the left of the temperature control. Or it can look like arrows arranged in a circle.

For those whose car, the question of using or not using this mode largely disappears by itself, as it takes care of the cleanliness and air temperature.

The principle of recycling is applicable not only to cars, but is also actively used at home and in industrial areas.

For example, built-in hoods in the kitchen, which work on the same principle as described above, allow you not to connect to a stationary ventilation pipe, but work through integrated filters.

Ventilation and heating system VAZ 2109

As you know, on the VAZ 2109, interior heating is provided by air heated by a radiator. On the VAZ 2109, heating and ventilation of the cabin are interconnected and represent a kind of special system.
In this article, we will consider the general principles of the VAZ 2109 heating and ventilation system.

Heating system

As a rule, the heating system of a VAZ 2109 car consists of several main elements and assemblies, shown below.

heater

The heater or stove itself is the main link in the heating system. It is fastened with 4 nuts in the passenger compartment under the bolts.
There are air ducts installed on the stove, which are fixed to the instrument panel from below. Sealing gaskets are required in their design.

What is the oven made of?

The heater of the VAZ 2109 system consists of:

• 2 plastic casings interconnected by brackets (fastening brackets are connected along the perimeter);
• Special harness, laid in the grooves for sealing;
• An electric fan that forces air into the passenger compartment and is screwed on top of the stove;

Note. The motor is mounted on the stove so that its dismantling is convenient and does not cause any difficulties.

• Heating radiator, which is installed in the heater casings;
• faucet;
• The cooling system pump, which circulates fluid through the radiator;
• Stove handles that allow you to control the heater.

Furnace handle control

You can achieve the most comfortable conditions in the cabin if you move the stove control knobs and adjust the position of the nozzles in the following way:

• The upper right knob regulates the air supply to the legs of the driver and front passenger (if the position is extreme left - the supply is maximum, if the knob is in the extreme position on the right - the supply is blocked).

• The top left knob controls the airflow to .
• The lower knob regulates the temperature of the air that enters the passenger compartment (leftmost position - cold air, rightmost position - hot).
• The left rotary button, visible in the photo above, connects the stove fan. It will increase the air supply.
  The button has 4 positions: 0 - off, 1 - initial speed, 2 - medium speed, 3 - maximum speed.

If the air temperature outside is minus 20 degrees Celsius, the stove starts to provide the maximum heating mode automatically.
The indicators in this case are as follows:

• +20 degrees Celsius is provided in the vehicle interior;
• +25 degrees Celsius is provided in the area of ​​\u200b\u200bthe legs of the passenger and driver.

Radiator

This is one of the most important parts of the car heating system. Unfortunately, during the passage of a certain amount of time begins to flow.
Traces of antifreeze on the passenger mat or under the mat are a symptom of a heater radiator leak. In this case, on the VAZ 21093, the interior heating will be completely broken and the radiator will have to be replaced.

Types of radiators

For the VAZ 2109, there are several main types of radiator.
The most popular are:

• Aluminum original;
• Aluminum aftermarket;
• Copper.

Of all this trinity, the most expensive is a copper radiator, which can be soldered in case of emergency and which is largely more reliable than the others.
less reliable, but cheaper. The original one costs about 700 Russian rubles, while the non-original one can be bought for 400 rubles.
The design of both types of aluminum radiators is different:

• The plates in the original radiator are much denser than in the non-original version.
• The heat exchange area in a non-original radiator is less than in the original one.
• The construction of the aluminum original radiator is much stronger.
• On the original radiator, the air begins to warm up already at a coolant temperature of 60 degrees, and in a non-original one only at 90 degrees and above.
• Inside the original radiators there are special coolant swirlers made in the form of spiral ribbons. They significantly increase work efficiency, because the coolant does not “fly” through the radiator, but circulates slowly, giving off heat more efficiently.

Radiator replacement

It is needed if the old one is no longer functioning efficiently enough.
The replacement is carried out in the following way:

• The front panel is unscrewed.
• The radiator is dismantled and removed carefully from its place.
• A new one is being installed.

Note. Self-taught masters recommend removing the radiator from the bottom of the instrument panel, where the lower shelf prevents this from being done. This shelf is sawn off, and after installing a new radiator, it is mounted on self-tapping screws, and in the future its removal will be an easy task.

On the VAZ 2109, the interior heating system is notable for exhaust ventilation, which provides air exhaust from the passenger compartment. This ventilation is located on the back of the VAZ 2109.
In addition to providing air suction, exhaust ventilation is also carried out through the vacuum that occurs at the deflectors when the vehicle is moving.

valve

Exhaust ventilation on some versions of the VAZ 2109 is equipped with valves on a regular basis, which serve to increase the amount of fresh flowing air in the cabin.
In wet weather, these same valves help reduce fogging of the windows. Basically, the VAZ 2109 models are not endowed with these valves, and most owners install them on their cars on their own.
What needs to be done in order to install the valve:

• It is enough to make technological holes in the body.
• Remove the rear bumper.
• Mark seats for valves.
• Insert valves.

Features of the operation of the stove and its refinement

Owners of a VAZ 2109 car are often worried that over time the stove starts to heat up badly. Needless to say, driving in such a car will already be uncomfortable.
In such cases, only upgrading the stove can solve the problem.

Improvement methods

Lots of ways. Below are a few of them.

Throttle lever

So:

• You can simply tighten the stove damper control cable to solve the problem. 1-2 turns of the cable are made, located on the damper control lever (the lever itself is located on the stove body, near the gas pedal).

Note. The joints of the air ducts and the edges of the heater damper are pasted over with foam rubber, which is not completely compressed.
In this regard, a gap of several millimeters is formed, and the damper does not close completely. The above method will help you set the lever properly.

• You can get to the control lever in another way. There is a place on the driver's side and you need to try to reach out with your hand and tighten the lever, be sure to turn on the heater fan.
  During the adjustment process, the left ear will be in the area of ​​​​the air duct nozzle and thus it will be possible to hear how the sound of the outgoing air changes.

Heater faucet

The reason for the inefficient operation of the heating system may also be the incomplete opening of the stove faucet. Such a problem, by the way, is found in almost all front-wheel drive cars of the Vaz family.

• The solution to the problem can be the tension of the valve control cable and the subsequent fine-tuning of the control lever to the maximum open position.

Note. In this case, it is possible that the valve will now not fully close. But this is not the problem, but that after adjusting the lever, the damper may lose its tightness and begin to leak (seen in the photo).
In this case, it can be advised to wrap the leak with a cloth that has been soaked in sealant and fix it all with cold welding.

air ducts

The reason for the poor functioning of the heating system may be leakage of air ducts. The air that is blown by the heater fan partially goes into the cracks, and the air flow, thereby weakens and cools down.

• The solution can be complete sealing and gluing of the joints that are located in the places where air follows from the stove to the exit.

Air locks

In addition, the reason for the poor operation of the stove can be air pockets formed in the heater radiator.

• The solution would be to stop the car with the front part on some hill. Then you should open the heater tap completely and press the accelerator pedal several times.

Above were some ways to fix problems with the heating and ventilation system of the VAZ 2109. The instructions and advice given by experts is a chance to “cure” your car with your own hands, thereby saving a lot on repairs.
As you know, the price of technical procedures in the service station is not low, and if they are carried out regularly, the family budget will noticeably become scarce. It is recommended to use photo and video materials in the process of independent work.

Long gone are the days when a car was valued only for its technical characteristics and appearance, today a very important component of the car is its comfort. Several car systems are responsible for creating comfort, including air conditioning and its further development - climate control. These two systems will be discussed in this article.

Purpose of the air conditioning system

Until the 30s and 40s of the last century, most cars, especially trucks, did not have a closed cab and interior, so their comfort depended on the weather - in the cab of the old car there was, in fact, the same “weather” as on the street . Modern cars in this regard have gone far from their predecessors, but even in a sealed cabin without special measures, there will be the same frost or heat as outside.

Engineers have been trying to solve the problem of the microclimate in the car interior for a very long time, and to date, considerable progress has been made in this matter. But if it’s quite easy to heat the car (it’s enough to send air from the engine compartment into the cabin - this is how the air heated by the running engine is utilized), then cooling the air is a much more difficult task. But there is a solution to it - this is a car air conditioner.

The air conditioning system is designed to cool the air inside the car, which creates a favorable microclimate regardless of the outside temperature. The first car air conditioners appeared quite early - already in the 1930s, but until the end of the 1950s, the most expensive cars in top trim levels were equipped with air conditioning systems.

By the 1960s, technology had reached a level that allowed the production of efficient car air conditioners in small dimensions and at a low price (and the first air conditioners took up at least half the space of the luggage compartment, and had a considerable cost), which led to their most widespread use. However, this situation was observed only in the USA - in European countries, car air conditioners began to spread only from the 1980s, and in Russia even from the 90s.

Today, air conditioning in a car is no longer a luxury, but a necessity, although it is still offered as an option in most cases. Climate control systems are also widely used, in which air conditioning also plays the main role, but this system is unlikely to become standard for cars of different classes in the near future.

The device and principle of operation of the air conditioning system

The operation of an air conditioner is based on simple principles of thermodynamics, simple household refrigerators also work on the basis of the same physical laws, and an air-conditioned car is, in essence, a real refrigerator.

The operation of the air conditioner is based on a vapor-compression refrigeration cycle, which in the general case is reduced to the following. A gaseous refrigerant of a sufficiently low temperature is compressed by a compressor (the pressure of the refrigerant increases by about five times) and is supplied under high pressure to a condenser - a special radiator blown with air for cooling. In the condenser, the refrigerant, due to cooling and pressure increase, passes from the gaseous state to the liquid state, in this state it is supplied to the throttling device (where it partially evaporates) and to the evaporator - radiator, in which the liquid refrigerant is completely evaporated. Evaporation occurs with the absorption of heat, and this is what is used to cool the cabin air, which is driven through the evaporator. The heated refrigerant enters the compressor again and the cycle repeats.

This is how any air conditioner works, including car air conditioners. The latter consists of the following components:

Compressor;
- Capacitor;
- Condenser fan (usually a regular fan of the engine cooling system is used);
- Receiver-drier;
- thermostatic valve (expansion valve, pressure reducing valve, throttle);
- Evaporator;
- Evaporator fan;
- Sensors of high and low pressure;
- Piping system.

All components of the system are connected with copper or aluminum pipelines, the connections are hermetically sealed, so the whole system is closed and does not communicate with the atmosphere. The part of the system that includes the compressor, condenser, receiver-drier and half of the pressure reducing valve is called the high pressure side. Here, the refrigerant is in a liquid state under pressure up to 15-25 atmospheres. The system including the second half of the pressure reducing valve, the evaporator and the compressor inlet is called the low pressure side (or return line). Here, the refrigerant is under pressure of about 3-5 atmospheres. The side separators are, as it is easy to understand, a compressor and a pressure reducing valve.

The temperature of the refrigerant in different parts of the air conditioning system is not the same. So, at the compressor inlet (that is, at the exit from the evaporator), the refrigerant has a temperature of +10 ... + 20 ° C, the refrigerant is compressed in the compressor, as a result of which its temperature can reach + 70 ... + 90 ° C. In the condenser, the refrigerant is cooled, but its final temperature (at the exit from the condenser) depends on the outside temperature - the refrigerant is on average 10-20 degrees warmer. After passing through the pressure reducing valve, the refrigerant is strongly cooled, its temperature can take negative values. But in the evaporator, the refrigerant heats up to the above values.

It is necessary to say about the purpose, design and operation of the main components of the air conditioning system.

Complexity

Lift

Not marked

Rice. 12.1. Scheme of the movement of air flows in the ventilation, heating and air conditioning system: 1 - windshield vents; 2 - dampers for the distribution of air flows to the windshield deflectors and to the instrument panel deflectors; 3 - instrument panel deflectors; 4 - air ducts for heating the driver's and passengers' legs; 5 - damper for the distribution of air flows to the instrument panel deflectors and to the air ducts for heating the driver's and passengers' footwells; 6 - heater radiator; 7 - cabin air filter; 8 - damper of the recirculation system; 9 - air intake box; 10 - air intake in the car; 11 - fan impeller; 12 - fan motor; 13 - air conditioner evaporator; 14 - drainage hole for draining condensate; 15 - damper of the temperature controller; 16 - housing block of the heating and air conditioning system.

Rice. 12.2. Schematic diagram of the movement of the refrigerant in the air conditioning system: 1 - combined pressure sensor; 2 - section of the high pressure pipeline; 3 - receiver-drier; 4 - service valve of the high pressure line; 5 - condenser (air conditioner radiator); 6 - fan of the condenser and radiator of the cooling system; 7 - air conditioner compressor; 8 - section of the low pressure pipeline; 9 - service valve of the low pressure line; 10 - heater fan; 11 - evaporator; 12 - thermostatic valve.

The heating (air conditioning) and ventilation system is a single complex that provides the most comfortable conditions in the car, regardless of weather conditions and driving conditions. The system includes a heater (increases the air temperature in all operating modes of the system), an air conditioner (reduces air temperature and humidity), a fan and air ducts with a filter (provide air exchange in the cabin, purify the air from dust), as well as a control unit (controls all elements systems to obtain the desired comfort parameters).
Note.
The air conditioning system is installed on a part of the production of cars.

Outside air can enter the passenger compartment through the door windows with the windows down and the air blower located in front of the windshield. The air from the blower can enter the passenger compartment through the windshield blower nozzles, side and center nozzles, and also through the lower nozzles of the heater housing.
The interior heating and ventilation system is controlled autonomously from the air conditioning system when performing the function of heating and ventilating the interior, removing frost and condensed moisture from the windshield, as well as blowing the door windows. At the same time, the main elements of the heater work even when the air conditioner is turned on. The units of the heater and the evaporator of the air conditioner are made in one block.
To clean the air supplied to the passenger compartment from the dust contained in the street air, a filter is installed in the heater unit.
The car is equipped with a liquid-type heater. It is integrated with the engine cooling system by two hoses running in the engine compartment.
The main components of the heater (fig.12.1): – heater heat exchanger 6 (radiator), designed to heat the air entering the passenger compartment with the heat of the liquid cooling the engine; – fan 11 with electric drive 12 (air blower), providing a regulated supply of outside air to the dampers of the heater and air conditioner; – damper 15 of the air temperature regulator coming from the heater to the passenger compartment, the amount of air passing through the heater heat exchanger and outside air passing bypassing the heat exchanger depends on the change in its position; – flaps 2 for distributing the air coming from the heater through the air ducts into the passenger compartment or for blowing the windshield.
On fig. 1.7 shows the panel of the control unit for heating (air conditioning) and ventilation of the car interior, installed on the console of the instrument panel.
Switch 18 (see Fig. 1.7) for the intensity of air supply to the passenger compartment operates regardless of the position of the air distribution and temperature regulators and controls the fan speed by changing the voltage in the electric motor power circuit.
The air flow distribution controller 16 and the temperature controller 27 control the heater dampers using cable drives.
The air conditioning system is controlled by means of controls located on a panel shared with the heater.
A compressor-type air conditioning system is installed on a Chery Tiggo car (Fig. 12.2).

Compressor mounted on the engine using a special mounting bracket and is driven by a V-ribbed belt for the drive of auxiliary units.
Compressor of axial-piston type with variable capacity. The compressor shaft is mounted in an aluminum housing on two needle bearings and sealed on the side of the drive pulley with an oil seal. The compressor has seven pistons with Teflon O-rings. Lobe type valves. The capacity regulator is built into the compressor housing.

The drive pulley is mounted on a double-row ball bearing and constantly rotates when the engine is running. When the air conditioner is turned on, the torque from the pulley to the compressor shaft is transmitted through a friction clutch with an electromagnetic drive. The compressor circulates the refrigerant in the system and creates the pressure necessary for the refrigerant to flow through the thermostatic valve opening.
Helpful advice.

If the system is working properly, when the air conditioner is turned on, a click is heard - this is the clutch, under the action of an electromagnet, engages with the drive pulley, and the compressor rotor begins to rotate.
But during the operation of the air conditioner, the following compressor malfunctions may occur.
1. If, when the air conditioner is turned off, the clutch makes extraneous sounds during rotation, heats up, or a burning smell appears, then its bearing has probably begun to collapse. In this case, the bearing must be replaced. In some advanced cases, it may be necessary to replace the compressor clutch or its constituent parts.
2. If, after turning on the air conditioner, a click is not heard, then it is possible: - there was a refrigerant leak, and the electrical control circuit blocks the compressor from turning on; - the pressure sensor in the system has failed; – the electric circuit of management is broken; - The coil of the electromagnetic clutch burned out; – the engine control unit blocked the compressor from being switched on for some reason.
3. If the clutch rotates easily and freely, but when the air conditioner is turned on, extraneous noises are clearly audible or the engine even stalls, then the compressor is most likely stuck.
The internal pump part of the compressor cannot be repaired, the compressor will have to be replaced.
4. And the last, most insidious option. A click is heard, the clutch easily rotates the compressor shaft, and there is no coolness in the cabin. In this case, perhaps the compressor only pretends to work, but in fact it does not pump anything.
Only an experienced specialist in the presence of control and diagnostic equipment can establish the truth. If your compressor has been diagnosed as "lack of compression", then you should be sure that a good specialist has identified the problem. If in doubt, you can re-diagnose and make sure that the cost of purchasing and replacing the compressor is indeed inevitable.
The exact cause of the malfunction can only be determined as a result of a complete diagnosis in a service center for the repair of automobile air conditioners.

In some versions of the compressor, on cover 8 (see Fig. 12.4) of the reed valve block, an emergency pressure relief valve can be installed. In the event of an increase in pressure in the system due to a failure of the pressure sensor or other emergency situations, when the set maximum pressure is exceeded, the valve membrane is destroyed, and part of the refrigerant is released into the street.
As a rule, after this, the emergency valve does not have sufficient tightness.
Therefore, after eliminating the causes that caused the increase in pressure and the discharge of the refrigerant, the valve must be replaced.

Condenser (air conditioner radiator) multi-flow type is installed in front of the radiator of the engine cooling system. The condenser cells are made of flat thin-walled aluminum tubes with internal longitudinal baffles to increase rigidity and external fins to improve heat transfer. Tanks aluminum with flanges for connection of tubes.
The tanks are divided into sections along the height, therefore, passing through the condenser, the refrigerant flow changes direction several times.
In the condenser, vapors of the refrigerant compressed by the compressor are condensed and the heat released in this case is removed to the surrounding air.
When the air conditioner is turned on, the engine control unit turns on the power circuit for the electric fan of the engine cooling radiator. This improves the heat exchange in the condenser and reduces the pressure in the air conditioning system.
Helpful advice.

At least once a year, preferably before the start of summer operation, wash the fins A of the condenser honeycombs from adhering dirt, dust and anti-icing agents B. This will improve heat transfer, reduce pressure in the system and increase the service life of the system elements.
Do not use high pressure water jets to clean the condenser. This can cause damage to the B thin-walled fins.
Even with regular washing, the need to replace the condenser occurs much more often than we would like. The fact is that he is the first to take on the flow of anti-icing reagents, dirt and pebbles from the road. And its tube walls are thin In most cases, the condenser is damaged by corrosion in the third or fourth year of operation.
If the tightness of the condenser is broken as a result of corrosion, then it is more expensive to repair it. Even if the master of argon welding manages to patch the hole, a leak may soon appear elsewhere. By the way, the pressure in the system on hot days can reach up to 25–28 bar.
In addition, the complex structure of the condenser tube should be taken into account: along it is divided into channels by partitions, so it is highly likely that after welding, some of the channels will be blocked. Accordingly, the dissipated power will drop and the operation of the air conditioner will deteriorate, especially in traffic jams and in hot weather.
After each experiment with condenser patching, you will need to pay for removal-installation, welding of the condenser and charging the system with refrigerant. So it is better to immediately install a new condenser. Instead of an expensive original one, it is quite possible to buy a cheaper condenser from authorized spare parts manufacturers.

Receiver dryer installed in the engine compartment on the right side. The body of the receiver is non-separable, made of aluminum alloy. Pipelines are attached to the body of the receiver using flange connections. Inside the housing there is a filter element and a cavity filled with desiccant (silica gel) granules. The liquefied refrigerant passing through the receiver is cleaned of possible impurities, dirt and moisture.
Note.

In case of repair or replacement of elements of the air conditioning system, if the system was in an open state (some components were removed, pipelines were destroyed, etc.), the receiver dryer must be replaced. Without this, after filling the system, the refrigerant will not dry out and acids may form inside the system, which will destroy the parts of the air conditioner from the inside. When purchasing a new receiver, make sure that the connecting pipes are tightly closed with process plugs. A receiver that has been stored without plugs is unusable, even if it is brand new.

thermostatic valve block type is located under the hood near the engine shield. Has flange connections. After passing through the throttling hole in the valve body, the liquid refrigerant abruptly reduces its pressure and begins to boil. A regulating element is installed in the valve body, which changes the flow area of ​​the throttling hole depending on the pressure and temperature of the refrigerant. The control element is set at the factory and is not adjusted during operation.

Evaporator located in a common building with a cabin heater. Manufactured from flat aluminum tubes with external fins to improve heat transfer. Passing through the evaporator tubes, the boiling refrigerant actively absorbs heat from the air blowing over the outer finned surface of the tubes. The air is cooled and blown into the vehicle interior by a fan.
An electronic thermostat sensor is attached to the evaporator. It monitors the surface temperature of the evaporator and, when it drops below the freezing point, sends a signal to the engine control unit to turn off the air conditioning compressor - the evaporator is defrosted.
Note.
When the air passing through the evaporator is cooled, the water vapor contained in it condenses.
Condensate drains through the drain tube under the bottom of the car. If the ambient humidity is high, a puddle of water may form under the vehicle. This is an indirect sign of the health of the air conditioning system.
During the operation of the car on the outer surface of the evaporator, wet from condensate, particles of road dirt and dust settle.

This layer is an excellent environment for life and rapid reproduction of putrefactive bacteria and fungal cultures. Over time, an unpleasant odor develops in the car. It is especially strong when the air conditioner is turned off and in humid weather.
To minimize the risk of this problem, it is necessary when buying a car to carry out preventive treatment of the evaporator with special chemicals and regularly clean the drain tube. If the smell still appears, you should contact a specialized car air conditioning repair service to flush the evaporator. In case of very strong contamination, the evaporator will have to be replaced.

Pipelines connect all elements of the air conditioning system into a single sealed circuit. Pipelines and their fastening flanges are made of aluminum alloys.

Rice. 12.3. The design of the hose of the flexible insert: 1 - outer protective sheath; 2 - fabric cord of the power frame; 3 - plastic sealing layer; 4 - inner oil-resistant layer To connect the mutually moving elements of the system, pipelines in separate sections have flexible inserts (Fig. 12.3) made of synthetic materials.

O-rings made of neoprene are installed at the joints of the individual elements of the system. During the repair of the system, when disconnecting sections of pipelines, sealing rings must be replaced.

The pipelines also have two service valves for connecting diagnostic and refueling equipment.
The valves are closed with threaded caps to protect them from dirt. The caps are marked with the symbols H and L for the high and low pressure lines, respectively.
Note.

This is how the service valves of high A and low pressure B are located on the pipelines.

The valves are equipped with spools, similar in design to the spools of the wheel tires, but differing from them in size.
A special key is used to turn the spools in and out.
Warning.

It is forbidden to check the presence of refrigerant in the system by pressing the spools of the service valves, since after such a check the valve spool may not close completely, and the refrigerant will leak from the system!

Pressure meter combined type is installed on the section of the high-pressure pipeline in the engine compartment. It forcibly turns off the air conditioning compressor in case of depressurization of the system (no more than 1.7 bar) and an emergency increase in pressure in the system (no less than 28 bar) in order to protect the compressor from overloads. At a pressure of 18 bar, the sensor turns on the power supply circuit for fan 6 of the radiator of the engine cooling system, which improves heat transfer in the condenser and reduces pressure in the air conditioning system (see Fig. 12.2).
Note.
The sensor is installed on the pipeline using a threaded fitting with a shut-off valve, so when replacing or checking the sensor can be unscrewed without violating the tightness of the system.
Warnings.

When replacing the sensor, sealing ring A on the threaded fitting of the pipeline must be replaced with a new one and lubricated with oil for the air conditioning system before screwing on the sensor.

Check the condition of the sealing surface on the sensor body. The surface must be clean and smooth.
If there are signs of corrosion, the sensor will have to be replaced.
Coolant. The system is charged with R134a refrigerant. Special oil has been added to the refrigerant to lubricate the compressor. It is strictly forbidden to use other types of refrigerants and oils in the system.
Helpful advice.

The type of recommended oil is indicated on a label affixed to the compressor housing.
Warning.
The air conditioning system is charged with high pressure refrigerant.
Contact of liquid refrigerant on human skin causes severe frostbite, so all work related to maintenance, repair or dismantling of air conditioning system elements should be carried out, if possible, in specialized service centers equipped with professional technological equipment. When working on your own, take precautions. Wear protective goggles.
Notes.
During the operation of a car air conditioner, situations periodically arise when maintenance of the air conditioning system or its repair is required. For this, modern diagnostic and repair equipment is used. The most common situation is the depressurization of the system and the release of refrigerant from it.

Highly sensitive halogen leak detectors with sound indication are used to detect leaks.
In some complex cases, the method of ultraviolet diagnostics of the tightness of the air conditioning system is used.

The method consists in the fact that a special dye is introduced into the system in microdoses.
In places of microflows, the dye, together with the refrigerant, gradually comes to the surface of the system elements.

During the inspection of the system, under the influence of ultraviolet rays of a special lamp, the dye begins to glow (fluoresce)

and refrigerant leaks become visible. It should be noted that the dye does not have any negative effect on the system.
It can be in the refrigerant and circulate through the system for an arbitrarily long time and serve its purpose only when a leak occurs.

After repairing the air conditioner, it is necessary to evacuate and charge the system with the appropriate refrigerant (R134a). The volume of refueling of the car air conditioner for each car model is individual.
To carry out high-quality refueling of a car air conditioner, you need:

– precision manometric blocks with special connecting tips;

– two-stage vacuum pump for complete removal of air and water vapor from the system;

– high-precision (division value d5 g) scales for dosing the charged refrigerant.
Due to the specific features of the repair of the air conditioning system, this section describes only the work on the removal and installation of individual elements and the system control unit. Work related to charging the system with refrigerant should be carried out in specialized service centers.