The individual components of the refrigerant circuit are connected by hoses to form a closed system. In the system, driven by the compressor, the refrigerant circulates. The circuit is divided into two sides:
- The part between the compressor and the expansion valve is called the high pressure side (yellow/red).
- Between expansion valve and compressor we speak of the low pressure side (blue).
In the compressor, the gaseous refrigerant is compressed and thus strongly heated. It is pressed through the capacitor under high pressure. Heat is extracted from the strongly heated refrigerant, causing it to condense, i.e. change its state from gaseous to liquid.
The dryer, the next station, separates impurities and air inclusions from the now liquid refrigerant. This ensures the effectiveness of the system and protects the components from damage due to contamination.
Now we go from the dryer to the expansion valve. This valve can be seen similar to a weir. Before the weir, it maintains a constant pressure, while after the weir, due to the increase in volume, this pressure can be released. Since the expansion valve is located directly in front of the evaporator, the expansion of the refrigerant passes into the evaporator. During evaporation, i.e. when the aggregate state changes from liquid to gaseous, evaporative cooling is released.
The evaporator is similar to the condenser a heat exchanger. It has an enormously large surface area, through which it releases the evaporative cooling into the environment. This emitted cold is now blown by the ventilation system into the vehicle interior, where it is responsible for the comfort of the passengers. On the low pressure side, the journey of the now gaseous refrigerant goes back to the compressor, where the cycle starts all over again.
Operation and optimal use of the air conditioning system
In most systems the evaporator is integrated in the heating box. This means that the air conditioner can be used all year round (to cool in summer and to provide dehumidified/dry warm air in winter). Only at temperatures below 4 to 5 °C is the air conditioning often of no use, as it is automatically switched off depending on the manufacturer and system.
To get dehumidified hot air: turn on the air conditioning and set the heater controls to red = warm. This creates a pleasant dry air in the vehicle and fogged windows are cleared very quickly. To further speed up this process, direct the air towards the windshield.
For vehicles equipped with recirculating air control: for rapid dehumidification, rapid cooling or after driving in tunnels, make sure that the system switches back to fresh air.
When parking, you will often find a buildup of water under the vehicle if the air conditioner has been in operation. This is normal and a direct consequence of dehumidification.
Parking in the shade
On sunny days, park your car in a shady place if possible. If the car is parked in the sun on a hot day, the interior temperature can rise to 60 °C. If you pay attention to some small things, you will have the security of cool climate faster:
- If possible, park in the shade
- Set the air conditioning and ventilation to maximum when you start your journey
- Drive with the windows open for the first few minutes – it will get pleasantly cool faster that way.
Compatible / sensible cooling
An air conditioning system lowers both the temperature and the humidity of the air in the vehicle interior. For health reasons, the inside temperature should be 5 to 6 degrees below the outside temperature (recommended: at least 22 °C).
Care and maintenance of the air conditioning system
Air conditioners for vehicles are equipped with a dryer. This component has two functions. It has a desiccant to remove moisture from the refrigerant and also acts as a filter.
It is very important that air conditioning systems are kept completely dry. Moisture in the system converts to acid and damages many components.
The dryer should therefore be replaced every two years, or when the system has been opened for extensive repairs.
Disinfection of the heat exchanger / evaporator
For your health! – with this component, evaporative cooling (humidity) is released into the ventilation system. Alternating between cooling and heating provides the ideal breeding ground for spores, bacteria and viruses. Only regular disinfection can help – look out for a musty smell in the vehicle!
Refrigerant / oil
Air conditioners can lose up to 15% of refrigerant per year due to natural evaporation through the system hoses, resulting in reduced performance.
If the cooling is not sufficient, or if you have the impression that the system has a fault or a leak, please contact your hella service partner.
To ensure maximum performance and trouble-free operation, you should have the air conditioner serviced annually. Run the system for a few minutes at least once a week. your refrigerant contains lubricants – this keeps the shaft seal of the compressor lubricated. Otherwise, the refrigerant can leak at the seal. If nothing is done about the refrigerant loss, rust may form on the internal parts.
Replacing / cleaning the cabin air filter
contamination of this component will reduce the performance of the air conditioner resp. To fog the windows. Therefore, this component should be checked annually or every 15 years.000 km to be changed/cleaned.
If the engine overheats too much when the air conditioner is running, DO NOT use the air conditioner until the vehicle has been inspected and the cause of the problem has been corrected.