Auto air conditioner parts

Air conditioner: key insights into component performance, mounting, diagnostics, and durability

An air conditioning system is used to cool the air inside a car. It ensures comfort inside the vehicle regardless of the ambient temperature.

Design of an air conditioning system

A vehicular air conditioner is made in the form of an air-tight system, in which refrigerant circulates. This is a substance that generates heat when compressed into a liquid state and absorbs it when expanding into a gaseous one. Refrigerant is pressurised by a compressor. It is driven either by the engine crankshaft, an electromagnetic clutch, or its own electric motor.

After activating the air conditioner, the compressor compresses the refrigerant, resulting in it being heated to 80-90 °C. After that, it is directed to the condenser, where counter-current air flows or a fan blow on it. These temperature fluctuations cause the condensation process to take place and the refrigerant passes through the receiver-drier as it’s turning into liquid, where dirt and moisture are eliminated from it. After that, the cooling agent passes through the thermostatic control valve and enters the low-pressure pipeline and then the evaporator, cooling down while entering a gaseous state. In front of the evaporator, is a fan that spreads the cooled air across the cabin. After that, the refrigerant returns to the compressor.

Sensors and control units control the operation of all these components.

Maintenance tips

• Keep the engine compartment clean. Clean dust, dirt, and debris from the condenser from time to time. Remove any accumulated salt deposits from it.
• Make sure that the tubes are securely fastened. If you notice that they’re loose, tighten the fasteners.
• Perform maintenance the air conditioner on a regular basis. Do not ignore the recommendations for topping off the refrigerant: It tends to evaporate through the pores of the hoses, so over time the amount of cooling agent in the air conditioning system decreases.
• Switch the system on in winter as a preventive measure. This will allow for lubricating its internal components, protecting them from corrosion and drying out. The unit running for about 15 minutes is sufficient. However, note that the procedure should be carried out in a warm room such as a garage, covered parking space, etc.
• Try to clean the evaporator and replace the cabin filter twice a year.
• If the car has been left in the sun for a long time in hot weather, air it out before turning on the air conditioning. This will reduce the load on the compressor and minimise the risk of getting ill.
• Do not refill the air conditioning system yourself. Without suitable tools, you will not be able to control the pressure in the system. Excess refrigerant is very dangerous because it can cause hydraulic shock and the destruction of the compressor.
• When the system is on, close the windows. If warm air from the street constantly gets into the car, all components of the air conditioning system will wear out prematurely.

Malfunction symptoms

Noises and humming coming from the compressor whenever the air conditioner is on or off indicate that the pulley bearing has worn out. However, if the noise appears only when the engine is running, the compressor itself is likely to be faulty. The compressor has to be replaced. A reduced cooling efficiency, as well as white foam in the inspection window, (if there is any), indicate that the system is leaking. If a condenser is contaminated, the system may shut down on its own. The same problem occurs when the thermostatic control valve is clogged. Simultaneously, evaporator tubes may get covered with ice accompanied by interruptions in the cold air supply. Similar problems can be observed when the pressure sensor is defective.

Malfunction causes

Deterioration of the compressor and other elements is most often caused by a lack of lubricant, which can be explained by a low level of refrigerant or by the system being out of use for a long time. Therefore, the air conditioner should be switched on at least once a week. Corrosion that damages the radiator and heater can be caused by a filter-drier failure, if, for example, it has not been replaced during depressurisation of the system.

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