Working principle of Chery car air conditioners and common problems

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Working principles and common issues of air conditioning components: 2. Air conditioning shutdown mode (the air conditioning may shut down automatically or stop working in the following operating conditions): (1) High-load engine air conditioning shutdown mode: This mode is designed to maintain engine performance (this feature is particularly evident in vehicles with small engines; especially in vehicles with a 0.8QQ engine, when the accelerator is pressed too quickly, the air conditioning shuts down automatically to ensure optimal engine performance. There is also a situation where the air conditioning shuts down even if the accelerator is not pressed very quickly, and this phenomenon is common in vehicles equipped with Siemens electronic control systems. In such cases, it is necessary to update the ECU. ) (2) Throttle fully open – air conditioning shutdown mode: This ensures optimal power delivery (this situation occurs under severe driving conditions; such a problem generally does not arise. However, if the throttle is kept at a high position for an extended period, the ECU will shut off the air conditioning system to maintain the engine’s power output. ) (3) Engine speed too high – air conditioning shutdown mode: to protect the air conditioning system ； (4) Air conditioning shutdown mode when the engine coolant temperature is too high: This mechanism is designed to protect the engine. When the air conditioning is turned on, the vehicle’s load increases, and the temperature of the condenser rises, all of which can lead to an increase in the engine’s coolant temperature. To protect the engine, its electronic control system will automatically shut off the air conditioning once the coolant temperature exceeds a certain threshold. Generally, the shutdown temperature set by the engine controller is as follows: In Delphi’s fuel injection systems, the air conditioning compressor is shut off when the coolant temperature exceeds 108C, and the compressor can only start again when the coolant temperature drops below 106.5C ； When the A/C is running ； The cut-off temperature of the Sanling electronic control system is 115C ； The cut-off temperature of Siemens CVT is 118C ； The Fengyun series comes in two cut-off modes: 108 and 112°C ； The cut-off temperature for the Siemens 372 series is 110.25C ； The problem of the air conditioning being turned off due to high engine temperature usually occurs in vehicles that have accumulated a high mileage. After the vehicle has traveled a certain distance, both the engine’s and the radiator’s cooling capabilities decline; especially when the engine operates under heavy load for extended periods, which leads to excessively high engine temperatures, and as a result the system automatically shuts off the air conditioning. (5) Ambient temperature-based air conditioning shutdown mode: to ensure driving performance ； (6) Air conditioner shutdown mode when the evaporator temperature is too low: to protect the air conditioning system ； (7) Air conditioning cut-off mode due to excessive pressure in the air conditioning system: To protect the air conditioning system ； The most common problems in summer are poor cooling performance or no cooling at all. The reasons for these issues are as follows: (1) Insufficient cooling capacity: Excessively high pressure on the high-pressure side (exhaust side), which may be caused by an excessive amount of refrigerant being installed, or too much refrigerant having been removed ； (2) No cooling: The pressure on the high-pressure side is too high, while the pressure on the low-pressure side (suction pressure) is too low; there may be a blockage between the compressor and the liquid storage dryer ； (3) Insufficient cooling capacity or no cooling: The pressure on the high-pressure side is low, and the pressure on the low-pressure side is also low; this may be due to leaks at the connections or components of the gas refrigerant lines, or insufficient refrigerant charge ； (4) Insufficient cooling capacity: high pressure and low temperature. This type of fault is usually caused by a damaged air conditioning compressor or an excessive amount of refrigerant, or it may also be due to poor heat dissipation by the condenser ； Under normal circumstances, when the system is exposed to air for an extended period of time, especially after a break in the air conditioning lines, air enters these lines as well as the dryer bottle, damaging the desiccant and potentially causing blockages in the lines, which in turn affects the system’s cooling capacity. Therefore, when repairing such vehicles, it is necessary to replace both the dryer bottle and the expansion valve in order to resolve the problem fundamentally. 4. The refrigerant charge for Chery’s vehicle models is as follows: QQ series: with a fixed-displacement compressor, the refrigerant charge is 500g ； Wind & Cloud series: Variable-displacement compressor; refrigerant charge is 850g ； Flag Cloud series: Fixed-displacement compressor; refrigerant charge amount is 850g ； Tiguan series: Variable displacement compressor; refrigerant charge is 850g ； Son of the East: Variable-displacement compressor; refrigerant charge is 850g ； 5. The lubricating oil used in refrigeration systems is generally referred to as refrigeration oil. This oil is essential for ensuring the proper operation of the compressor: 1. Lubrication function: Compressors are machines that operate at high speeds, and the surfaces of components such as bearings, pistons, piston rings, connecting rods, and crankshafts need to be lubricated in order to reduce friction and wear, extend their service life, lower power consumption, and improve the cooling efficiency ； 2. Sealing function: The compressors used in vehicles are semi-hermetically sealed, and an oil seal is required on the compressor’s input shaft to prevent refrigerant leakage. Lubricant is needed for the oil seal to function. At the same time, the lubricating oil on the piston rings not only serves to reduce friction but also acts to seal the compressed steam. 3. Cooling effect: Moving friction surfaces generate high temperatures, and refrigerant oil is needed to cool them. Insufficient cooling by the refrigerant oil can lead to overheating of the compressor, excessive exhaust pressure, a reduced cooling efficiency, and even damage to the compressor. 4. Reduce compressor noise. Precautions for using refrigerant oil: 1. Refrigerant oils of different grades cannot be mixed, as this will cause deterioration ； 2. Refrigeration oil absorbs water very easily, so the bottle containing the oil should be tightened immediately after use ； 3. Rotten refrigerant oil must not be used. When refrigerant oils of different grades are used together, chemical reactions occur due to the differences in antioxidants added to each grade, resulting in deterioration and damaging the individual refrigerant oils ； 4. Refrigeration oil does not provide cooling; moreover, it can impair the heat exchange efficiency of the heat exchanger. Therefore, it is only allowed to be added in the specified amount, and excessive use is strictly prohibited. If the amount added exceeds the standard level ； 5. Liquid Storage Drier: The liquid storage drier is an important component in the automotive air conditioning system, using a thermal expansion valve as the throttling device. The load on the evaporator changes continuously due to variations in temperature and humidity inside the vehicle; moreover, in some systems, refrigerant is lost due to minor leaks. Therefore, it is necessary to have a reservoir to store excess refrigerant, which can then be supplied to the evaporator when needed. The liquid storage section of the liquid storage dryer unit serves this purpose. 6. Desiccant: A desiccant is a solid substance used to remove moisture from gases, liquids, or solids; it is placed between two screens inside the liquid storage dryer. Its ability to absorb moisture depends on its capacity, the type of desiccant, and the ambient temperature. Therefore, when maintaining air conditioning systems or filling them with refrigerant, it is essential to prevent moisture from the air from entering the refrigeration system. The liquid storage dryer cannot be repaired; if it is damaged or becomes ineffective, it must be replaced. 13. How to use it: 1. Release hot air first before turning on the air conditioner. If the car is parked in the scorching sun for a long time, do not use the air conditioning right away after starting the vehicle. First, open all the windows and turn on the external ventilation mode to expel the hot air. Once the temperature inside the vehicle drops, close the windows and turn on the air conditioning. The air conditioner should not be turned on and off frequently to prevent damage to the system. 2. When the air conditioner is on in the vehicle, the driver should not smoke inside. If you smoke, set the air conditioner’s ventilation mode to “external circulation”. 3. Do not use the air conditioner for too long after parking. Some car owners, in order to stay cool, close the doors and windows of their vehicles in areas with poor ventilation such as garages or dark corners, turn on the air conditioning, and rest inside the car. This can easily lead to poisoning or even death of the passengers inside, as car exhaust contains large amounts of toxic substances; in places where ventilation is poor, these substances accumulate in high concentrations and can enter the car through the ventilation system, causing the passengers to be poisoned. 4. Do not pile up items near the air intake to prevent it from getting blocked, which could impede air circulation in the air conditioning system. Especially during periods of strong sandstorms or in autumn when leaves fall, it is essential to ensure good ventilation around the intake openings. 5. Turn off the air conditioning a few minutes before reaching the destination (where you will park), and then turn on the natural airflow. Raise the temperature inside the air-conditioning ducts before parking to eliminate the temperature difference with the outside environment, thereby keeping the air-conditioning system relatively dry. Avoid the proliferation of excessive mold due to humidity. It should be noted that for sedans with a displacement of over 1.4 liters, the air conditioning performance is generally satisfactory. However, in some compact cars with a displacement of 1.1 liters or less, the low engine power results in poor air conditioning performance; in fact, water may start boiling even after driving for a short distance with the air conditioning on, especially on hot summer days. Therefore, there are two key points to keep in mind when using air conditioning in summer: First, if the engine’s temperature rises too high due to the increased load caused by the air conditioning, it is necessary to stop using the air conditioning until the engine temperature returns to normal. II. It is necessary to avoid using the air conditioner at idle speed for long periods in hot summer weather while the vehicle is parked, as the air conditioner cannot be cooled effectively, which can lead to damage due to excessive system temperature and pressure. III. Air conditioning generally consumes 10–15% of the engine’s power, so its use leads to a significant increase in fuel consumption. Therefore, to reduce fuel usage, it is necessary to minimize the frequency of using air conditioning. Daily use of car air conditioning: During operation, the car air conditioning system causes air to flow through the blower, the evaporator of the cooling system, the small tank in the heating system, and the air ducts. As long as the air-conditioning system blower is turned on or the intake mode is set to indoor circulation, air will enter the aforementioned system regardless of whether the cooling unit is in use. Over time, the surface area of the aforementioned devices accumulates a lot of dust, moisture, bacteria, and other contaminants, which can cause damage to the human respiratory system and skin as well as trigger allergic reactions. This directly affects the health of those who use them. Additionally, the air conditioning system itself may suffer from problems such as reduced cooling efficiency and lower airflow. Under normal circumstances, the air conditioning filter should be cleaned every 5,000 kilometers or every 3 months, and it should be replaced every 20,000 kilometers or every 12 months. This ensures that you can enjoy a fresh and clean interior environment in your car, thus safeguarding your health. The expansion valve has three main functions: (1) Throttling to reduce pressure, thereby converting the high-temperature, high-pressure liquid refrigerant coming from the condenser into a low-temperature, low-pressure misty form of refrigerant that is easier to evaporate, so that it can enter the evaporator; this process serves to separate the high-pressure and low-pressure areas within the entire refrigeration system. (2) Automatic adjustment of the refrigerant flow: As the cooling load and compressor speed change, the system requires that the flow rate of refrigerant entering the evaporator also change accordingly in order to maintain a constant temperature; the expansion valve can automatically adjust the flow rate of refrigerant entering the evaporator. (3) Control the flow rate of the refrigerant to prevent liquid slugging and abnormal overheating of the system; the expansion valve uses a temperature sensor as its sensing element to regulate the flow rate. 10. Evaporator: The evaporator is a component of the refrigeration system, where the refrigerant absorbs heat and vaporizes. Hot air is forced to pass through the fins and coils of the evaporator, and the heat from this air is absorbed by the vaporized refrigerant, which is then carried to the condenser in the system. Its purpose is to ensure that the refrigerant, as it leaves the evaporator and enters the compressor, is a low-pressure, slightly superheated vapor. If too much refrigerant enters the evaporator, the result is that the pressure of the refrigerant within it becomes too high, preventing it from vaporizing quickly; as a consequence, the air conditioner fails to cool. This will cause an excess of liquid refrigerant to leave the evaporator and enter the compressor, resulting in liquid slugging. If too little refrigerant flows into the evaporator, the refrigerant will evaporate or vaporize too quickly long before it passes through the evaporator, and as a result the air conditioner will be unable to cool. 11. Condenser: The function of the condenser is the opposite of that of the evaporator; the heat-carrying refrigerant in gaseous state is turned into a liquid or condensed in the condenser. To achieve this, the refrigerant must release heat, and the forced-flowing air, namely the air passing through the condenser, carries away this heat from the condenser, causing the gas to condense. The heat discharged from the refrigerant is equal to the heat absorbed by the evaporator, which causes the refrigerant to change from a liquid to a gas. When the refrigerant enters the condenser, it is almost 100% vapor; only a very small amount of this vapor liquefies in the pipes, but such an amount is negligible and does not affect the operation of the system. The refrigerant leaving the condenser is not always in liquid form, as only a certain amount of heat energy can be removed from the condenser within a given time, so a small amount of refrigerant may leave the condenser in gaseous state. Since the next component is a drying tank, this state of the refrigerant does not affect the operation of the system. The inlet of the condenser must be at the top, so that the condensed refrigerant can flow to the bottom of the condenser and, under pressure, enter the liquid storage and drying tank through the liquid piping. The refrigerant in the condenser is a mixture of liquid and gas under high pressure, requiring extra caution during maintenance.