E30 series BMW 3

since 1983-1994 of release

Repair and car operation

Being once a prerogative of only smart cars, the conditioner nowadays becomes an integral part of the increasing and bigger number of "ordinary" family cars. By estimates of experts, by the beginning of the following eyelid a half of all European cars will be on sale with the conditioner as by a standard accessory.

Central air, simply speaking, selects at air heat, and also reduces level of its humidity. Therefore, air in car salon always more cool and not such damp that creates feeling of freshness.

How the microclimate in salon is created?

Standard central air consists of several working knots connected among themselves by tight system of tubes. It is filled with a coolant which passes from a liquid form in gaseous and back, transferring heat from salon.

The most important detail on which overall performance of the conditioner depends, the regulating gate which is established on the evaporator placed in salon of the car is. The coolant in the form of liquid under a high pressure arrives via regulating gate in the evaporator where it is sprayed in the form of a gazo-drop mix (fog). The regulating gate can be needle or such as a diaphragm. We will consider the first option.

In the needle gate there is a small opening, and the needle located in an opening is capable more or to block less it, changing thus effective section. The needle is put in action from a temperature-sensitive element placed in the evaporator.

Liquid coolant, passing through a small opening in the gate, evaporates and turns into gas under low pressure. This process is accompanied by sharp temperature drop. The opening less, the becomes colder халадагент, that is the temperature in the evaporator can be regulated, entering or deducing a needle from an opening. The temperature of a surface of the evaporator should be close to a water freezing point, but not below it, differently on the evaporator ice that will complicate movement of air and heat transfer to a coolant will be formed.

As it was already told, instead of the needle gate sometimes, the diaphragm is established. In it there are no moving parts therefore the coolant expense in the evaporator is not regulated, but its giving is supervised by means of the thermorelay or the pressure relay. Having turned into gas of low pressure, the coolant passes on the evaporator (heat exchanger) and selects heat at air in salon. For bigger efficiency of this process the heat exchanger is supplied with edges. Moisture containing in air is condensed on an external surface of the heat exchanger and merges out of salon. Air, having passed through the heat exchanger, comes back to salon colder and dry.

Saved up by a coolant it is warmly necessary to give to the atmosphere, for what the coolant by means of the compressor goes to the condenser (is one more heat exchanger located usually in a forward part of the car).

The compressor, which task – to banish a coolant on system tubes, transferring heat from low temperature level on higher, works by a principle of the pump and is brought by a belt from the engine via the electromagnetic coupling that the conditioner could be disconnected. When the compressor works, he creates depression which "exhausts" a gaseous coolant from the evaporator.

In the compressor pressure of a coolant raises, and it arrives in the condenser, but already in the form of gas under a high pressure. In the condenser gas turns again into the liquid, heat thus containing in it dissipates from a condenser surface in the atmosphere.

From the condenser the coolant – already in the form of liquid under pressure – again moves on regulating gate, and the cycle repeats.

Additional "lotions"

In practice the described base scheme includes still some knots, in particular, a receiver dehumidifier which often (but not always) is mounted between the condenser and the regulating gate. This device (it sometimes call "accumulator") filters a coolant and deletes from it moisture. Sometimes the dehumidifier is supplied with the color indicator which shows when it it it is time to replace its (it means that it gathered a moisture maximum). System of tubes (between the condenser and the evaporator) sometimes build in viewing glass, and then it is possible to watch a coolant condition (existence of unnecessary vials etc.).

The supercharger banishing air through the evaporator, and the fan enter into central air with the thermostat, raising overall performance of the condenser also. Usually the system includes also the pressure sensor with the switch. It is located near a receiver dehumidifier and operates operation of the compressor and the condenser fan, and also supports optimum pressure in system (a miscellaneous for different systems).

In the majority of systems over the evaporator fastens also a heating element. The air stream with the help of "a mixing zaslonka" is distributed between the evaporator and a heater so that to give it desirable temperature.

And how with ecology?

Until recently in automobile conditioners R12 freon was applied. Then it was established that containing in it хлорфторуглероды perniciously influence an ozone layer therefore now to let out R12 in the atmosphere it is forbidden. Besides, under the influence of an open flame of R12 allocates deadly gas phosgene. It is still authorized to fill with it conditioners of former releases as operation of these conditioners is authorized also.

Respectively, the price for R12 freon raises for 5–10 % a month. Eventually it becomes such what to "recharge" old systems begins is simply ruinous. Already now R12 freon costs in the west of $150 for kg, and two years ago cost $65. In modern systems more "harmless" coolant – R134А is used.

The systems calculated on R134A, are arranged so that at service and repair there were no leaks. For this purpose in the right places special valves and other adaptations are established.

Theoretically, R134А can be downloaded and in the old conditioner, having made corresponding changes. However, this coolant of percent on 15 is less effective, than R12 therefore the conditioner of old type with it will worse work. Besides, there is one more problem: the coolant of R134А filters, though is weak, through the hoses made of pure rubber. Special hoses are necessary for this substance with an internal nylon braid. At the same time in old systems so-called "zayershenny" connecting unions which are capable to break through this braid are applied. In a word, it is at present more favorable to use an old coolant.

Generally, there are the so-called "replaceable" coolants which are intended for replacement of R12 and not demanding expensive alteration of system on R134А, but as experts speak, it is impossible and to admit them on a gun shot to the conditioner. Some of these substances contain butane which can ignite in system, besides, it will ruin the test equipment.

If you want to pass from R12 to R134А, it is best of all to change oil together with a coolant (mineral on synthetic) in system to establish a new receiver dehumidifier to replace rubber hoses and to check work of all knots. Then there is a hope that the system will well work.

That everything worked

In order that central air well worked, it is necessary to be able to address with it. For example, many do not know that the conditioner only then will effectively work, when in the car all windows, and also the hatch are closed. Quicker to cool salon in very hot day, it is necessary for a minute - another to open all doors and when the car will blow – everything to close and turn on the conditioner (at the working engine).

Draining influence of the conditioner reduces a zapotevaniye wind and lateral glasses of salon therefore sometimes the conditioner is useful for including at the same time with an oven. However, some climatic systems do not provide simultaneous operation of the conditioner and an oven.

In central air there is an oil which circulates together with a coolant. If the system long stays idle, its some details, in particular, neoprene laying, dries up and collapses, leaking. Therefore it is desirable to turn on once a week the conditioner not less, than for ten minutes, including in the winter that oil greased all knots of system.

What it is possible to repair?

Conditioners are not subject to "house", amateur repair. The coolant – substance whimsical, for its complete pumping and downloading new is required the professional equipment and to provide full tightness, special high-sensitivity devices for identification of leaks are necessary.

If the conditioner broke, means, at least, it is necessary to replace any details, including special tubes and a fitting, but there is a set of their standard sizes. And special blooming adaptations are applied to fastening of tubes to a fitting.

So, if you had problems with the conditioner, rely only on experts. Address in firms which make difficult repair, and not just download the disappeared coolant. If the coolant "left" system, in the beginning it is necessary to find the reason, differently a new coolant will disappear in the same way!

Similarly if at you jammed the compressor, it is simple to replace it insufficiently: in some months it again will jam. It is necessary to remove in the beginning from system shaving and other garbage, and then to wash out it special solution or nitrogen. It is necessary to replace also a receiver dehumidifier (in it there was a shaving) and to download a fresh coolant.

Receives damage the condenser more often. It is located before an automobile radiator and protected by only a radiatorny lattice.

The second problem is failure of the needle gate (it is hammered by dirt). Cleaning the gate, it is necessary to remove from it dirt, instead of to push it inside!

There are also other problems – for example, the compressor rustles. Usually, it speaks about its close end.

It is easy to check a condition of a driving belt. The compressor is given in some cars by a separate belt. It is successful option. However modern cars are often equipped with a long "multipurpose" belt which actuates at once some devices, often, including, and the water pump. So, if the bearing of a leading pulley of the compressor of the conditioner suddenly will jam, you will not leave anywhere, yet will not find a belt of the smaller size to "bypass" the compressor!

Other aspects

If after all there was a leakage of a coolant through rubber hoses, their replacement is quite problematic, as it is difficult reliable загерметизировать new hoses on an old aluminum fitting.

Keep in mind that the conditioner can not turn on, if the surrounding temperature is lower set or if pressure in system is much lower (leakage of a coolant) or above the optimum.

To violations in operation of the conditioner bring also excess of oil, a coolant, hit into air or moisture system, strong pollution of edges of the condenser or the evaporator, malfunction of system of cooling of the car (overheat), and also proskalzyvany couplings of the compressor.