1, type automotive air conditioning system
1, according to the driving modes: Detached (a dedicated engine to drive the compressor, cooling capacity, stable, but the high cost, large size and weight, and more for large and medium-sized passenger cars) and non-independent (air conditioning compressor driven by an automotive engine, cooling performance influenced by the engine, poor stability, and are used for small passenger cars ).
2, according to the air conditioning performance is divided into: a single functional (refrigeration, heating, ventilation systems are each mounted, a separate operation, noninterference, used for passenger cars and trucks on the large) and being of one-piece (cooling, heating , the common ventilation fan and duct, is controlled in the same control board, can be divided into temperature controlled mixing warm and cold air, respectively, and a combined work of cold or warm wind can operate simultaneously work multiple mixed temperature controlled car).
3, when the control mode is divided by (toggle function keys on the control panel temperature, wind speed, wind direction control) and electrically controlled pneumatic manual adjustment (by the vacuum control means, a good air-conditioning function election key, can automatic control of temperature and air flow within a predetermined temperature).
4, according to the control modes: automatic adjustment (using the calculated comparison circuit, by presetting of sensor signal and the control signal adjusting means to automatically adjust the temperature and air volume) and a computer-controlled automatic adjustment (to control microcomputer central, interior air to achieve all-round, multi-optimal control and regulation).
2, the arrangement of the air conditioning system
arrangement of different types of air-conditioning system vary. Car is currently widely used integrated heating and air-conditioning systems. Pattern is arranged to an evaporator, a radiator heater, a centrifugal blower, and the like are assembled control mechanism, referred to as the air conditioner assembly.
3, consisting of automotive air conditioning system
Modern refrigeration system of an air conditioning system, heating systems, ventilation and air cleaning device and control system.
automotive air conditioning compressor is generally formed predominately (Compressor), electrically controlled clutch, a condenser (condensers), an evaporator (Evaporator), an expansion valve (expansionvalve), drier (receiverdrier), pipe (Hoses), is condensed fan, vacuum solenoid (vacuumsolenoid), idle speed control systems and other components. Automobile air-conditioning of the high pressure line and a low-pressure line. It includes a compressor output-side high pressure side, the high-pressure pipe, a condenser, a drier and a liquid conduit; low-pressure side comprises an evaporator, the accumulation, a return line, the input side of the compressor and compressor oil pool.
drier mdash; mdash; storage actually a refrigerant and the refrigerant absorbing moisture, impurities apparatus. On the one hand, it is equivalent to the fuel tank of the car, was leaked refrigerant extra space to add refrigerant. On the other hand, that it is like a air cleaner, filter out impurities doped in the refrigerant. Also drier with some silicone material acts to absorb moisture.
condenser and an evaporator mdash; mdash; Although they are not the same name, but similar structures. They are covered with a metal sheet for heat dissipation in a row around the bend pipe, in order to achieve devices with outside air heat exchange pipe material. It refers to a condenser for condensation refrigerant heat pipe in which a liquid from the gaseous cemented. Radiator The principle is similar to the engine (only difference is that the water tank has a liquid only), so it is often installed at the front, with tanks together to enjoy the cool breezes from the front. Where short condenser where to cool, so that condensation heat. Opposite the evaporator and condenser, which is a refrigerant from the liquid into gas (i.e., evaporator) to absorb heat properties.
4, the original automotive air-conditioning workLi
car air conditioning system compressor, a condenser, a receiver drier, an expansion valve, an evaporator and a blower and so on. Using brass (or aluminum) and high pressure rubber tube connected to a closed system between the various components. Working refrigeration system, refrigerant circulates in different states within this closed system, and each cycle of four basic processes: 1 compression process: compressor suction temperature low-pressure refrigerant gas at the outlet of the evaporator, it compressed into high temperature high pressure gas discharge of the compressor. 2, the cooling cycle: superheated refrigerant gas high temperature and pressure into the condenser, due to the reduction of pressure and temperature, the refrigerant gas is condensed into a liquid, and discharges a large amount of heat. 3, throttling process: temperatures and higher pressure refrigerant liquid through an expansion device after the larger volume, a sharp decline in pressure and temperature, a mist (fine droplets) discharging the expansion device. 4, an endothermic process: mist-like liquid refrigerant enters the evaporator, and therefore much lower than the boiling point of the refrigerant within the evaporator temperature, it is evaporated into gas refrigerant liquid. It absorbs surrounding heat in the evaporation process, and then temperature low-pressure refrigerant vapor and enters the compressor. The above process cycle is performed, to reduce the ambient air temperature of the evaporator.
domestic automotive air conditioning has developed over the years, but the overall design and manufacturing level lower than abroad. The development of the domestic automotive air conditioning since the late 1980s and early 1990s, in which the representation of supporting enterprises, the production of bus air-conditioning air-conditioner plant in Shanghai Peoples, now Air International (Shanghai) Co., Ltd., the production of air-conditioning Shanghai Santana Delphi automotive Air conditioning systems Co., Ltd., the production of red car air conditioning Air conditioning Co., Changchun FAW Jack Purcell. With the increasing popularity in recent years, management information systems, domestic manufacturers began to try batches introduction of information management systems for enterprise development, such as Shanghai Delphi Automotive Air Conditioning Systems Co. introduction of product data management system IPM / PDM, unified management of product design information and process information, to form project information database for effective information exchange and sharing of resources and management information database ERP system through a computer network, and ultimately meet the company’s overall plan CIMS standards, to achieve the company’s information technology. However, the domestic automotive air conditioning industry started late, there is a scattered, chaotic, poor pattern. vaporLack of car air-conditioning manufacturers design strength, technological backwardness. In terms of several major domestic automobile air-conditioning plant, it is still in the stage of imitation of foreign air-conditioning system. Although the introduction of design software UG, Catia and other three-dimensional modeling software, but software utilization rate is not high, designers virtually no evaporator, a newly developed design capabilities heaters and blowers.
Compared with foreign enterprises, China’s automotive air conditioning industry started relatively late, automotive air-conditioning mainly dependent CKD assembly. With the rapid development of automobile industry, the growing market demand for automotive air conditioning. At that time, most companies do not meet the production needs of technical equipment, many companies have introduced technology and production equipment from abroad, there are many places to start investment, fight the automobile air-conditioning project. Since then, the country set off a hot car air conditioning, large-scale restructuring thus appear. For example, the air-conditioning plant Mudanjiang merger FAW Group, Shanghai Delphi Automotive Air Conditioning Factory and American automotive air conditioning joint venture, Shashi Valeo Automotive Air Conditioner Factory and the French joint venture, Hunan Huada air conditioning factory joint venture with Japan Jack Purcell, Yantai Shougang automotive air-conditioner plant joint venture with Japan’s Denso Corp., Yueyang Hengli Air-cooling equipment Co., Ltd. was Beijing Huacheng Group Holdings. From the beginning of the 1990s, the domestic automotive air conditioning industry began rapid and steady development. Because enterprises imported technology and equipment from different countries, the industry is no unified technical standard to follow, fragmented, coupled with the lack of core technology, China’s automotive air conditioning industry is under threat from foreign counterparts.
5, automotive air conditioning system maintenance
a, select the appropriate air temperature. Of course in the summer, many people like the temperature is very low tone. Little do they know when the temperature is set too low, it will affect their health, so the air-conditioning temperature adjustment must be appropriate. Most appropriate body temperature is 20 ℃ to 25 ℃, Chaoguo 28 ℃, people will feel muggy. And below 14 ℃, people will feel cold. Thus, the vehicle air-conditioning temperature should be controlled at between 18 ℃ to 25 ℃, temperature is too low easily make people sick.
Second, the summer into the car and start circulating immediately. Car parked in the sun longer period of time, some owners like to start the car immediately open aKai air conditioning and open the inner loop that would allow the inside temperature drops a little bit faster. However, because the temperature inside the car is higher than the outside temperature, so this effect but not good. At first enter the car, you should open the window ventilation, and open the outer loop, the hot air are discharged. After the temperature inside other drops, and then into the circulation.
Third, it is well known to use air conditioning in the closed state. For automotive air conditioning too, if in the course of the door, the windows closed lax, it will make the poor cooling effect, but also a waste of fuel.
Fourth, the air conditioning vent freely adjust the direction. Some owners in the use of air conditioning, do not pay attention to adjust the air conditioning blowing direction, which is not conducive to play the best air conditioning. According to the sinking cold air, hot air rising principle, the correct approach should be, the outlet open air upward, down the outlet open heating.
Fifth, the open air for a long time. Some owners often in the car after the air conditioning has been open, but prolonged use of air conditioning will make the condenser pressure is too large, this will cause loss of refrigeration systems, because the air conditioning is a heavy burden on the engine, and the engine itself is a fever body, not to mention in hot weather. Some small cars even in this case there will be water boiling phenomenon, affecting driving also reduces the efficiency of air conditioning. So each time use of air conditioning should not be too long, if the inside temperature has reached a comfortable temperature, you can turn off the air conditioning, separated for a while to open.
Sixth, do not smoke in the air-conditioned car. Since the smoking compartment, smoke all of a sudden did not break out, irritates the eyes and respiratory system, is not conducive to health, if smoking should be adjusted to control the air conditioning and ventilation ldquo; discharge rdquo; position, the cabin smoke is discharged outside the vehicle.
Seven, not in an air-conditioned car for a long time suspended rest or sleep. As the car sealed, when the stopped vehicle, the vehicle interior air permeability difference, at this time if the open air rest or sleep, probably due to CO gas leakage into the interior of the engine exhaust causes poisoning, and even death.
eight, try not to use the air conditioner at low speeds. When driving in heavy traffic, not to improve the efficiency of the air conditioning at a higher engine speed operation, as this has a negative impact on the life of the engine and air conditioning compressors.
Nine, first turn off and then turn off air conditioning. Some owners often remembered after flameout turn off air conditioning, which is harmful to the engine, as this in the vehicleWhen times start, the engine will start with the air-conditioning load, such a high load can damage the engine. So after each stop should be closed and then turn off the air conditioning, but also in the vehicle should start two or three minutes after the engine is lubricated, and then turn on the air.
automotive air-conditioning not only to properly use, but also a reasonable maintenance. Here we will introduce the four methods on automotive air conditioning maintenance:
Method One: a comprehensive inspection of air conditioning.
should be the first use of air conditioning in summer to check the air conditioning system, such as by checking the refrigerant fluid reservoir and the air filter is too dirty, whether a foreign body such as a radiator.
Method II: Note that the clean air.
Some novice always wait until the air conditioning is not good effect, just think of clean air, it is not right. Should do the air conditioning filter should be changed regularly, because Beijing spring dust more catkins every now and then, these will stick in the filter, easy to grow bacteria that produce musty air conditioning, so the best after the annual spring replacement. In addition, the condenser should be cleaned regularly, and you want to remove the tank, can be completely cleaned.
Method three: after parking, the first not off the air conditioner.
Upon arrival the owner, usually directly after closing the door to leave the air conditioner. The fall and winter seasons, hot summer, huge temperature difference between inside and outside the car air-conditioning systems can lead to mold, mildew and then. So owners should turn off a few minutes before reaching the destination air-conditioning, open the natural wind, the temperature rise inside the air conditioning ducts, eliminating the temperature difference with the outside world, so as to maintain relatively dry air-conditioning system to avoid fungal reproduction.
Method IV: amount periodically open wind.
because some owners do not like the noise from the air conditioner open to high gear, so rarely or never open to the winds of the air conditioner. However, the use of air conditioning will be sucked into a lot of dust, wind can periodically open the air conditioning duct surface blow out dust, which is an air conditioner cleaning method remains simple. Further, also with a special cleaning liquid duct sterilizing, cleaning and deodorants.
automotive air conditioning compressor In a vapor compression refrigeration system, the compressor is one of the main components. Acting compression refrigeration system, the compressor is pressurized gaseous refrigerant to the condenser and cooled and condensed. Compressor provides the power to run the refrigeration system, and therefore power consumption.
was evaporatedGas compression type compressor refrigeration system is divided into two types: one for the velocity type, centrifugal. The other is a positive displacement type. In the automotive air conditioning and refrigeration systems in use today are positive displacement compressors.
Category automotive air conditioning compressor:
(1) a positive displacement compressor according to their structure can be divided into a reciprocating piston (abbreviated reciprocating) and rotary piston (abbreviated rotary).
reciprocating and rotary applications have different levels of automobile air-conditioner apparatus. Reciprocating come first, a model hitherto universal application (for example: BOCK, BITZER compressor), on a reciprocating compressor, the technology is more mature, has accumulated a wealth of experience in the production and use of low material requirements, easy processing and low cost. It can accommodate a wider range of pressure and cooling capacity range, high thermal efficiency. The downside is that, due to the reciprocal operation of the piston, the dynamic equilibrium performance is poor, limiting the improvement of the compressor speed, complex structure, multiple wearing parts, maintenance workload. The working volume of the rotational movement of the rotary compressor, without reciprocating mechanism, the dynamic balance of good performance, stable operation, small vibration, has a higher efficiency in its proper operating range. Further rotary compressor simple structure, small size, light weight, fewer parts, and high reliability. However, the rotary displacement of the compressor is small, typically smaller cooling capacity for air conditioning systems, such as automotive air conditioning systems.
(2) driving system vehicle air conditioning compressors may be divided into two types, non-independent and stand-alone based on its drive source.
non-independent is launched from the main car to drive the compressor, this approach is suitable for driving cars more than the main engine and compressor power-fung, not much of a vehicle, such as cars, vans, trucks and other works. This drive way small footprint, easy to maintain. But because part of the power consumption of the compressor main engines, can affect the acceleration performance of the vehicle, and the cold air conditioner will vary with vehicle speed.
Detached (or assisted), i.e., a separate motor arranged to drive the compressor. Since separate dedicated driver, independently of each other so that between the cars and the cooling effect of the air conditioner. But the drive way to occupy some car space, high cost, noisy, and maintenance support engine complex, it is not wide range of applications.
whether the host drive or auxiliary drive, automotive air-conditioning pressureOpen type compressor are employed, i.e., the compressor power input shaft extends beyond the body, connected by a pulley to the driver. Projecting portion of the body with the shaft seal to prevent leakage of the refrigerant.
automotive air conditioning compressor special requirements:
car running dynamic characteristics of the changing external environment on the performance and structure of the automotive air conditioning compressor made a number of special requirements, in:
(1) to good low speed performance, requires greater cooling capacity of the compressor and high efficiency when the vehicle load and low engine speed.
When the low power input (2) car at high speed, so that not only saves fuel, but also reduce the power consumption for the engine air-conditioning area, to improve the vehicle’s own power performance.
(3) to the compressor size and weight, saves vehicle space, ease of installation location, and material-saving fuel consumption.
(4) To be able to withstand the harsh operating conditions of the test, a high degree of reliability and durability. When idle, automotive engine compartment temperatures sometimes as high as 80 ℃ high condensation pressure, it is required to withstand high temperature and high pressure compressors and limited overload. Cars on the road there are always bumps vibration, which also requires compressor has a good seismic performance, and the leakage of refrigerant is reduced to a minimum.
(5) do not adversely affect the car. The compressor requires a smooth operation, low vibration, low noise, small impact on the start and stop of the engine speed, a small starting torque.
6, a comprehensive inspection fall automotive air conditioning
First check the adequacy of the refrigerant between the inlet conduit and the outlet conduit through the dryer felt temperature difference estimated or detected by the manifold pressure gauge.
Second, we must regularly clean the outlet and the cab of dust and dirt. This not only helps the car’s appearance, but also for the health of the driver and passengers are beneficial.
Third, the air conditioning system periodically check the refrigerant liquid level is normal. Check the fluid level method There are several, but the most common and easiest way is to use the peephole to check the dryer.
Fourth, check the compressor belt is good. If the belt pulley groove surface in contact with the bright side, and there ldquo start-conditioning; creak rdquo; noise, indicating a serious belt slippage should replace the belt and pulley; if the belt is too loose should be given to adjustment, or easy to make poor refrigeration air conditioning system [ 123] fifth, the air conditioning system to check if the hose fittings and traces of oil. Found leakage, should promptly consult a solution to the Maintenance Department.
In addition, the initial use of automotive air-conditioning season, the best air conditioning system for sterilization deodorization process, because the air conditioning system of long-term ldquo; leave rdquo; breeding ground for mold and mildew, it not only makes the air gives off an unpleasant musty taste, but also harmful to the health of occupants. This work can go to the repair shop, or may be purchased from specialized sterilization deodorant sprays themselves.
7, use, and maintenance methods
wanted to create a cool and comfortable interior space, the proper use of air conditioning and the necessary maintenance of air conditioning is a must essential. The correct use and maintenance methods, not only can bring you a cool summer, but also extend the life of air conditioning, air conditioning use the following ldquo; nine precautions rdquo; might be helpful.
First, the air conditioning retrofit must be cautious
does not advocate for car air-conditioning to be modified, because the original car’s engine and air conditioning are matched, such as random modification will affect the car’s performance.
Second, the air temperature is not too low
select the appropriate air temperature, the first step is conditioning maintenance. As the hot weather, many owners prefer to make the temperature too low, it will affect their health. Normally, the inside temperature and the outside temperature difference should be 5 ℃ to 6 ℃, i.e., the optimum temperature is 18 ℃ and conditioned to 25 ℃.
Third, the control outlet direction
since that enrich our knowledge of physics, we must remember that cold air sinks, the principle of hot air rising. Do not forget to learn and use, oh. Car air conditioning vent principles: The outlet upward open air, the outlet open heating down.
IV.Do not open the time is too long
We know you ldquo; not bad money rdquo ;, but still encourage you to properly close the air in motion. Prolonged use of air conditioning will make the condenser pressure is too large, this will cause loss of refrigeration systems. Thus, if the temperature inside the car has been let your peace of mind, it might be closed while air conditioning, it also rest, rest.
Fifth, open the appropriate winds of
afraid of the noise you already have long to enjoy the sweetness and light in only a small amount of wind? It is also appropriate to sing a song River of Go! Will inhale a lot of dust when air conditioning use, periodically open inner channel surface winds can blow out air of dust, the easiest method is most effective.
Sixth, the low-speed running off the air conditioner
try to close the air at low speeds, traffic jams do not improve conditioning performance of the engine at high speed operation, can shorten the life of the engine and air conditioning compressors.
VII switch procedures to remember
off the air conditioner and then to turn off, to ensure that the vehicle starts at the next engine start is simple; on the contrary, is not completely turned off along with the air conditioner starts the engine, so that high-load operation it will damage the engine. And many owners are often remembered after flameout turn off air conditioning. Therefore, each should be closed after parking then turn off air conditioning, it is best to start the vehicle two or three minutes after the engine is lubricated, and then turn on the air.
Eight, under the hot sun for a long slowdown with air conditioning
long vehicle parked in the sun, the compartment temperature is high. In such cases, immediately after the vehicle is started Do not use air-conditioning, should put all the windows are open for ventilation, the hot air out, and so the inside temperature drop, then close the windows, turn on air conditioning. In addition, it should not be frequently turned on and off air conditioning to prevent damage to the air conditioning system. Especially for cargo pickup models, in a short time when the shipment should avoid repeated switching air conditioning.
Nine, the car air conditioning as much as possible not to smoke
When the air conditioning inside the car, the crew not to smoke in the car. If smoking, please conditioning ventilation controls to their position outside the circle. Also note that, to keep in mind is not an air-conditioned car for a long time suspended rest or sleep. Because when a stopped vehicle, open the sealed compartment air conditioning ventilation is poor, if the open air at this time to rest or sleep, probably due to the leakage of harmful gases emitted from the engine into the car caused by poisoning, and even life-threatening.
8. The cleaning method according to
1, replace the dust filter
Conventional air conditioning system including the replacement of the filter cleaning, cleaning agents and remove clean-up. Replace the dust filter is the easiest way, but it can cost into the wind to keep them open, a little mechanical knowledge owners can clean up yourself. Most small car dust filters in front of the vehicle below the windshield, is covered launder. When replacing the dust filter, the hood can be opened first, remove the fixing clip stream sink, the flow tank is removed, you can see the dust filter. If the dust filter usage time is not long, the gas can be blown clean with high pressure; if already blocked, a direct replacement of the original dust off the filter, and installed as is trying to be difficult.
2, the outer circulation duct sterilization
There are various cleaning agents for cleaning the air-conditioning duct on the market, the owner can choose their own. Remove the dust filter, start the vehicle, the open air and placed outside the conditioning cycle stopper, the foam cleaning agent is sprayed onto the dust filter, the outer loop air conditioning winds suction duct cleaning agent, of duct , air conditioner evaporator and decomposition tank heater sterilization, eliminate the odor, dirt will flow out from the air conditioner into a liquid outlet. After the cleaning work is completed, it is preferable to replace the dust filter, air will be blown out of the car fresh air.
3, to the repair station clean
and replace the dust filter cleaning using a cleaning agent were carried out from the outside of the air duct clean air conditioning system, the air flow outlet if cleaning is still small, is not completely eliminate the odor, it is only to the repair shop lookout tank removed, replace the evaporator and manually clean air heating device housing. However, the bellows is usually installed in the instrument audience car, repair a lot of work, the costs are higher.
4, the use of ozone
using a high concentration ozone water to make sterilization of automotive air conditioning. It is understood, ozone water is one of the strongest oxidizing agent currently available that can be easily bacteria, fungi oxidative denaturation protein shell, quickly kill bacteria and spores, Escherichia coli, Staphylococcus aureus, hepatitis virus, oxidative decomposition cold virus. Ozone lively nature, At room temperature can be reduced to oxygen itself, it is the most environmentally friendly bactericidal substances.
9. A method for detecting the components of the cooling system
First, the refrigerant compressor inspection and testing Compression Refrigeration machine is the heart of automotive air conditioning system, which bears the compression system refrigerant and cycle to work. Generally should be checked and tested compression efficiency and leakage area.
the compression efficiency of the compressor is detected, without disassembling the system, manifold pressure gauge need to connect three groups tested. When a certain amount of refrigerant in the system, engine acceleration, when low pressure gauge pointer should be decreased, high pressure will be significantly increased, the larger the accelerator, the greater the decrease pointer, indicating a good performance of the compressor; if acceleration low table pointer decreased slowly and not decrease, indicating low compression efficiency of the compressor; if the accelerated low pressure gauge pointer almost no reflection on absolutely no explanation compressor compression efficiency.
The most compressor portions are prone to leakage seal (also as a seal). Since the compressor at a constant high-speed rotation, high temperature operation, shaft seal parts prone to leakage. When the compressor clutch coil portion and the chuck traces of oil, which will certainly seal leakage. Mainly
are likely to cause damage to the compressor:
1, dirty air conditioning system, particulate impurities are sucked into the compressor;
2, the system refrigerant or lubricating oil in excess, causing the compressor ldquo; liquid strike rdquo; damage;
3, operation of the compressor or the operation temperature is too high for too long;
4, compressor short of oil, serious wear;
5, an electromagnetic clutch for a compressor slippage while the temperature is too high friction;
6, power of the compressor is disposed too small;
7, manufacturing quality of the compressor is defective.
Second, the condenser and the evaporator detected The condenser and evaporator are automotive air conditioning system heat exchange container. High pressure and temperature refrigerant gas in the heat transfer to the outside in a condenser (heat release) is condensed (liquefied)Into a high-pressure liquid, thereby changing the shape of the refrigerant, but the pressure is substantially constant; pressure liquid heat exchanger (absorbing heat) generated by boiling (vaporization) of the heat in the external phenomena (cab) in the evaporator, so that continuously reducing the temperature of the space, a low pressure refrigerant gas after boiling (vaporization), thereby changing the shape of the refrigerant, but the pressure is also substantially unchanged.
The most common failure condenser and evaporator is clogged with dirt and leakage. Compressed air or nitrogen can be clogged with dirt and dried by blowing repeatedly washed until smooth and clean up.
condenser and an evaporator must often look clean dirt, or prostrate attention not to damage the heat transfer fins, to ensure that the heat transfer performance thereof.
As can be seen generally condenser leak from the outside, such as scratches Pengpo, traces of oil exudation and other leakage points. Because of low evaporator pressure leaks, condensation outer surface, hidden in the evaporation tank, generally difficult to detect.
The condenser and evaporator typically by leak tightness test (pressurizing test) acquisition, test pressure: condenser 2.0-2.4MPa; evaporator 1.2MPa.
Under normal circumstances, the surface temperature of the evaporator is very low, but not only a large amount of condensation frost or ice.
Third, the expansion valve and the bore of the tube inspection and testing The expansion valve is the expansion device and the orifice tube automotive air conditioning system refrigerant for air conditioning and refrigeration has a direct critical effect effect. High-pressure liquid refrigerant while passing through the expansion valve, automatically adjust the temperature of the incoming flow and the evaporation pressure of the evaporator so that it corresponds to the evaporation temperature.
The bore of the tube and an expansion valve which regulates mainly detected pressure is normal. When the system has a standard injection amount of the refrigerant at the engine idling, the low pressure at this time should be between 0.15-0.25MPa; otherwise explained expansion valve is not normal, open too large or too small. And the expansion valve opening bore of the tube is too large, the refrigerant through the plurality, the respective evaporation pressure and evaporation temperature is high, the temperature of the evaporator and a low pressure return pipe is not cold, the cooling effect; and the expansion valve opening bore of the tube is too small, less refrigerant through the respective evaporation pressure and evaporation temperature is low, the refrigerant can not be adjusted to meet the needs of the evaporator (heat exchanger), an expansion valve at the outlet of the evaporator and even frost, but the cooling the effect is still poor.
The expansion valve or orifice tube dirty blocking phenomenon is most common.When the system is too dirty, the filter accumulator dried desiccant (silica gel) broken, with the high-pressure refrigerant liquid flows into the expansion valve or orifice tube, plugged at most likely to form at the narrow passage. Causing the liquid supply is not normal, so that the system can not function properly. Dirty block occurs when the expansion valve or orifice tube, after the demolition of generally available carburetor cleaner repeatedly rinse, dried and treated with compressed air or nitrogen by dry and then refitted.
Since the evaporation temperature of the air conditioning and refrigeration systems generally above 0 ℃, so blocking phenomenon generally does not produce ice.