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As the conditioner works and what to do if it is out of order

Once a prerogative of luxury cars, air-conditioning is now becoming an integral part of more and more of the "ordinary" family cars. Experts estimate that by early next century, half of all European cars will be sold with air conditioning as a standard accessory.

The air conditioning system, simply put, takes away from the air warm, and also reduces the level of humidity. Therefore, the air inside the car is always cooler and not so wet, which creates a feeling of freshness.

How to create a microclimate in the cabin?

Standard air-conditioning system consists of several operating units interconnected by a sealed tubing. It is filled with refrigerant that changes from liquid to gaseous form and back, transferring heat from the passenger compartment.

The most important part, which determines the efficiency of the air conditioner, a control valve, which is mounted on the evaporator is placed inside the vehicle. The refrigerant in a liquid under high pressure flows through the expansion valve to the evaporator, where the gas is sprayed in droplet form a mixture (mist). Control valve can be a needle type or diaphragm. We will consider the first option.

Inside the needle valve has a small hole located in the bore and a needle capable of more or less overlap it, thus changing the effective cross-section. The needle is driven by a temperature sensor placed inside the evaporator.

The liquid refrigerant passing through the small hole in valve, evaporates and becomes a gas at low pressure. This process is accompanied by a sharp drop in temperature. The smaller the hole, the colder it becomes haladagent, that is, the temperature of the evaporator can be adjusted, the input or output of the needle hole. The surface temperature of the evaporator should be close to the freezing point of water, but no lower than it otherwise would be formed on the evaporator ice that impedes the passage of air and heat transfer to the coolant.

As already mentioned, instead of the needle valve sometimes set aperture. It has no moving parts, so the flow of refrigerant to the evaporator is not regulated, but its supply is monitored by a thermostat or pressure switch. Transformed into a low-pressure gas refrigerant passes through the evaporator (heat exchanger) and extracts heat from the air in the cabin. For greater efficiency of this process is provided with heat exchanger fins. Moisture in the air condenses on the outer surface of the heat exchanger and is drained number. The air passing through the heat exchanger is returned to the interior cooler and drier.

Accumulated heat refrigerant should be returned to the atmosphere, for which the refrigerant with a compressor to a condenser (heat exchanger is further disposed generally in front of the vehicle).

Compressor, whose mission - to drive the coolant through the pipes of the system, transferring heat from low temperature level to a higher, works on the principle of the pump and is driven by a belt from the engine through an electromagnetic clutch, the air conditioner can be disabled. When the compressor is operating, it creates a vacuum which "sucks" the gaseous refrigerant from the evaporator.

Inside the compressor the refrigerant pressure rises, and it enters the condenser, but in the form of a gas under high pressure. In the condenser the gas is converted again into the liquid, wherein the heat contained therein is dissipated from the surface condenser to the atmosphere.

Refrigerant from the condenser - in the form of fluid under pressure - is fed back to the control valve, and the cycle repeats.

For more "gadgets"

In practice, the described basic diagram includes some further components, in particular, the receiver-drier, which is often (but not always) be mounted between the condenser and the expansion valve. This device (sometimes referred to as "the battery") filters the refrigerant and removes moisture. Sometimes dryer is supplied with color indicator, which indicates when it is time to replace (it means that he scored the maximum moisture). The system of tubes (between the condenser and evaporator) are sometimes inserted into the sight glass, and then you can monitor the status of refrigerant (the presence of unwanted bubbles and so on. D.).

The air conditioning system also includes a blower, blows air through the evaporator and the fan with a thermostat, which increases the efficiency of the condenser. Typically, the system includes a pressure sensor and a switch. It is located next to the receiver-dryer and controls the operation of the compressor and condenser fan, and supports optimal pressure in the system (different for different systems).

In most systems, the evaporator is mounted over the heating element and another. Airflow by "mixing flap" distributed between the evaporator and the heater so as to give it the desired temperature.

What about the environment?

Until recently it was used in automobile air conditioners freon R12. Then it was found that it contained damaging effects of chlorofluorocarbons on the ozone layer, so now let R12 in the air is prohibited. Besides, under the influence of flames R12 allocates lethal gas phosgene. It is still allowed to fill their air conditioners previous releases as permitted and operation of air conditioners.

Accordingly, the price of freon R12 increases 5-10% per month. In the end, it will be such that the "recharge" the old system will simply wasteful. Already freon R12 is in the West $ 150 per kilogram, and two years ago was worth $ 65. In today's systems use more "eco-friendly" refrigerant - R134A.

Systems designed for R134A, arranged so that for maintenance and repair was not leak. To do this in the right places are special valves and other devices.

Theoretically, R134A can be downloaded in an old air conditioner, making the appropriate changes. However, this refrigerant is 15 percent less efficient than R12, so the old-type air conditioner will work with it worse. Furthermore, there is another problem: R134A refrigerant leaks, although slightly, by hoses made of pure rubber. For this substance requires special hoses with a nylon inner braid. At the same time, older systems use so-called "barbed" coupling connections which are able to break through this sheath. In short, at the moment is more favorable to use the old refrigerant.

In fact, there are so-called "vicarious" refrigerants, intended to replace the R12 and not requiring expensive rework system R134A, but, as experts say, and they can not fend on a gun shot to the air conditioner. Some of these agents include butane, which can be ignited within the system, moreover, it will ruin the test equipment.

If you want to go from R12 to R134A, it is best to change with the refrigerant oil (mineral to synthetic) in the system, install a new receiver-dryer, replace rubber hoses and check the operation of all nodes. Then, it is hoped that the system will work satisfactorily.

For everything to work

In order to air conditioning worked well, we must be able to handle it. For example, many do not know that the air conditioner will only work effectively when machine's closed all the windows and sunroof. To quickly cool the interior in a very hot day, you need a minute or two to open all the doors, but when the car will blow - all close and the air conditioner (engine running).

The drying effect of the air conditioner reduces the misting windscreen and side windows of the cabin, so sometimes useful to include air conditioning at the same time with the stove. However, some air conditioning systems do not provide simultaneous operation of the air conditioner and stove.

The air conditioning system has an oil which is circulated together with the refrigerant. If the system is idle for a long time, some of its parts, in particular, neoprene gasket, dry up and disintegrate, giving flow. It is therefore desirable once a week the air conditioner is not less than ten minutes, including the winter to allow the oil to lubricate all components of the system.

What can be repaired?

Air conditioners are not subject to "home", amateur repair. Refrigerant - naughty stuff, for its full pumping and injection of new professional equipment is required, and to ensure the full integrity, need special highly sensitive instruments for detecting leaks.

If the air conditioner was broken, so at least some parts need to be replaced, including special pipes and fittings, but there are plenty of sizes. And for fastening pipes to the fittings using special crimping tools.

So if you have any problems with air conditioning, just rely on professionals. Contact the company that produce the complex repair, not just pumped refrigerant evaporated. If the refrigerant is "gone" from the system, then you must first find the cause, otherwise the new refrigerant will evaporate in exactly the same!

Similarly, if you have jammed the compressor, it is not enough just to replace it: a few months later he again stuck. You must first uninstall the chips and other debris, and then rinse it with a special solution or nitrogen. We have to also replace the receiver-dryer (it remained chips) and download the new refrigerant.

Most often it takes damage the condenser. It is located in front of the radiator and the car is only protected grille.

The second problem is the refusal of the needle valve (it is clogged with dirt). Clearing valve, you must remove it from the dirt, and not to push it inside!

There are other problems - such as the compressor noise. Usually, it talks about his imminent end.

It is easy to check the status of the drive belt. In some machines, the compressor is a separate belt. This is a good option. However, modern vehicles are often fitted with a long "multifunctional" belt that drives the multiple devices, often including, and the water pump. So, if the drive pulley bearing air conditioning compressor suddenly jammed, you will not leave until you find a belt of smaller size in order to "get around" the compressor!

Other aspects

If, nevertheless, there was a leak of refrigerant through rubber hoses, their replacement is problematic since it is difficult to reliably seal the new hoses on old aluminum fittings.

Keep in mind that the air conditioner can not start if the ambient temperature is below the set or if the system pressure is much lower (refrigerant leakage) or above optimal.

Violations of the air conditioner and result in excess oil, refrigerant entering in air or water, severe pollution ribs condenser or evaporator cooling system malfunction (overheating) and slippage of the compressor clutch.