The failure of insufficient cooling of air conditi

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Some car air conditioning systems can even reach 0.2% Small size and insufficient cooling fault

now cars are basically equipped with air conditioners, which can provide drivers with a comfortable environment in the car in different seasons. However, after a long time of operation, the air conditioners will also have various faults, especially the phenomenon of insufficient cooling is also common. Therefore, today I want to discuss with you the principle of automotive air conditioners, the causes of insufficient cooling faults and maintenance

automobile air conditioning system is referred to as automobile air conditioning system for short. Its main purpose is to provide comfortable interior environment for passengers under any climate and driving conditions. People's requirements for the environment are often different due to their physique, age, gender, habits and health status. But under normal circumstances, the requirements of most people are roughly the same. Appropriate temperature, humidity, airflow and clean air constitute the three elements of air conditioning: temperature, humidity and cleanliness. A complete automobile air conditioning system is to create a comfortable environment in the compartment by adjusting the temperature, humidity, wind speed and ventilation

I. General composition and function of automobile air conditioning system

the air conditioning system is generally composed of the following five systems:

(1) refrigeration system: cooling or dehumidifying the indoor air or the fresh air entering the car from the outside, so as to make the indoor air cool and comfortable

(2) heating system: it is mainly used for heating, heating indoor air or fresh air entering the car from the outside, so as to achieve the purpose of heating and dehumidification

(3) ventilation system: it sucks the external fresh air into the car room for ventilation and ventilation. At the same time, ventilation also plays a good role in preventing the windshield from fogging

(4) air purification system: remove the dust, odor, smoke and toxic gas in the air inside the car, so as to make the air inside the car clean

(5) control system: it controls the temperature and pressure of the refrigeration and heating systems, and controls the temperature, air volume and flow direction of the indoor air, improving the normal operation of the air conditioning fixture automatic return to the initial position system

II. Working principle of automobile air conditioning and refrigeration system

(I) working principle of automobile air conditioning and refrigeration system

automobile air conditioning and refrigeration system consists of compressor, condenser, receiver dryer, expansion valve, evaporator and blower. As shown in Figure 1, all components are connected into a closed system by copper pipe (or aluminum pipe) and high-pressure rubber pipe. During the operation of the refrigeration system, the refrigeration system remembers different states. In this closed system, the circulating flow of plastic materials moves unless it is necessary or new materials. Each cycle has four basic processes:

1. Compression process: the compressor sucks in the low-temperature pressurized refrigerant gas at the outlet of the evaporator, compresses it into a high-temperature and high-pressure gas, and discharges it from the compressor

2. Heat release process: high temperature and high pressure superheated refrigerant gas enters the condenser. Due to the decrease of pressure and temperature, the refrigerant gas condenses into liquid and emits a lot of heat

3. Throttling process: the volume of refrigerant liquid with high temperature and pressure becomes larger after passing through the expansion device, and the pressure and temperature drop sharply. The expansion device is discharged in the form of mist (small droplets)

4. Endothermic process: the mist refrigerant liquid enters the evaporator. At this time, the boiling point of the refrigerant is far lower than the temperature in the evaporator, so the refrigerant liquid evaporates into gas. In the evaporation process, a large amount of heat is absorbed around, and then the low-temperature and low-pressure refrigerant vapor enters the compressor again

if the above processes are carried out repeatedly, the purpose of reducing the air temperature around the evaporator can be achieved

III. performance evaluation index of automobile air conditioner:

1. Temperature index: temperature index is the most important index. The most comfortable temperature for people is C ° and people will feel hot and dry if the temperature exceeds 28c °. If the temperature exceeds 40C °, it will be harmful to human health. Below 14C °, people will feel "cold". When the temperature drops to 0C °, it will cause frostbite. Therefore, the air conditioner shall control the temperature in the vehicle at 25C ° in summer and 18C ° in winter to ensure the normal operation of the driver, prevent accidents and ensure that the passengers travel in a comfortable condition

2. Humidity index: the index of humidity is expressed by relative humidity. Because people feel that the most comfortable relative humidity is 50%-70%, the humidity parameters of automobile air conditioning are required to be controlled within this range

3. Air freshness: due to the small space in the car and the high density of passengers, hypoxia and high carbon dioxide concentration are easy to occur in the confined space. Carbon monoxide in automobile engine exhaust gas, dust on the road and poisonous pollen in the field are easy to enter the compartment, resulting in air turbidity in the vehicle and affecting the health of passengers. In this way, the car air conditioner must have the function of filtering the air in the car to ensure the freshness of the air in the car

4. Defrosting function: in order to make the recycled plastic raw material particles full, because sometimes the temperature difference between the inside and outside of the car is too large, fog frost will appear on the glass, affecting the driver's line of sight, so the car air conditioner must have defrosting function

IV. troubleshooting method for insufficient refrigeration of automobile air conditioner

whether the performance of automobile air conditioner refrigeration system can meet the specified requirements is mainly based on whether the temperature in the compartment can reach the required index. Generally, if the vehicle air conditioner operates normally, when the external temperature is about 35 ℃, the temperature in the compartment should be kept at 20 ℃ -25 ℃. In order to meet this basic design requirement of automobile air conditioning, the cooling capacity of the air conditioning should be sufficient except for the good sealing performance of the carriage. So, what factors will affect the cooling effect of air conditioning? We believe that if the air conditioning effect of the car is insufficient, we can start from the following eight aspects

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