They are like the refrigerator for the car: air conditioners. What used to be equipment for luxury limousines is now also available in small cars. But air conditioning is not the same as air conditioning: There are some differences.
“In a closed circuit, liquid refrigerant evaporates and withdraws heat from the ambient air,” explains Carsten Graf of the ADAC the principle, which can be compared to a refrigerator. “On the other hand, the resulting gas is liquefied again with a compressor, whereby the heat is released again.
Although the basic principle is the same for all air conditioning systems, there are different types of compressors. “The simple compressors only have a fixed delivery volume and the refrigerating capacity cannot be regulated. They can only be switched on and off,” says Graf. More effective are semi- or fully automatic air conditioning systems that only provide the necessary cooling with compressors with variable delivery volumes.
The automatic system regulates the temperature automatically, for example when the car warms up in the sun. In addition, there are two or four-zone air conditioners: this allows the temperature to be set individually for each space, each zone. “Ultimately, the type of air-conditioning system the customer chooses depends on his comfort requirements and his wallet,” says Graf.
Try out the air conditioning system before buying a car.
“There are big differences in the air flow between the vehicles”. This is important for people who are sensitive to draughts. Frequent drivers in particular appreciate the automatic system. “For small cars used for short distances, a single-zone system also fulfils its purpose,” says Ulrich Köster from the German Motor Trade Association (Zentralverband Deutsches Kraftfahrzeuggewerbe).
But air conditioning systems do more than just provide driving comfort – they also increase safety. “At high outside temperatures, fatigue-free driving is also possible over longer distances,” says Mike Eismann, an expert in air conditioning systems at automotive supplier Continental. Fuel consumption can also be reduced. With open windows, greater air resistance increases fuel consumption – more than the air conditioning system consumes.
Automatic air conditioning system
An automatic air conditioning system is usually set between 22 and 24 degrees Celsius. “With manual air conditioning systems, care must be taken not to set the temperature and Air Con volume too high. An air flow that is too cold and punctual can be harmful to health,” says Eismann. It is more pleasant when the air flows through the central nozzles and partly into the footwell.
For the cooling to work well, it should be serviced regularly. The components are subject to normal wear and tear. Hoses and seals age, dry out and can leak. The refrigerant escapes and the cooling capacity decreases.
It therefore makes sense to regularly check the system and top up the refrigerant,” says Ulrich Köster. At the latest when the air conditioning system starts to smell, you should go to the workshop. “It makes sense to have an annual climate check in spring at the master garage. The most important components such as the compressor, condenser and evaporator are checked. He also recommends having a comprehensive air-conditioning service carried out every two years.
As a rule, however, the systems are inspected during an inspection according to the manufacturer’s specifications. The mechanics check the function, cold air, drive and compressor. Refrigerant does not wear out and the refrigeration circuit is a closed system. It therefore only needs to be refilled in the event of a leak, such as a defective compressor.
System should run every few weeks
Drivers cannot maintain the system themselves, but they can use it sensibly: “The system should run every few weeks so that the refrigerant oil is well distributed and the drive shaft and seals are lubricated,” says Graf. He recommends switching off the system in good time before parking to prevent a musty smell. This allows the ventilation system to dry out in just a few minutes. “Otherwise mould and bacteria can form on the moist evaporator,” he says.
The cabin air filter is also responsible for good air quality in the car. It filters dirty street air, while soot and pollen remain in the filter. “The filter should always be replaced once a year; for allergy sufferers, the replacement can be useful after a few months,” says Graf.