Condenser:
The condenser has an important function in a car’s air conditioning system. The refrigerant releases heat here and changes from gas to liquid.
From the A/C compressor, the refrigerant enters the condenser in the form of a superheated vapor. This is because the refrigerant has absorbed a lot of heat while cooling the air inside the car. In the condenser, the refrigerant is cooled down and its temperature drops below the boiling point. As a result, it changes into a cold liquid.
The condenser is somewhat similar to the radiator and is mounted at the front of the car, in front of the radiator. Just like the radiator, the condenser acts as a heat exchanger. It consists of bent pipes in a kind of serpentine arrangement, allowing airflow from driving wind or fans to pass through. In some vehicles we find condensers that are water-cooled.
In the image below, the inlet of the refrigerant is located at the top left and the outlet at the bottom right. The “filter/drier element” can be placed next to or on the condenser. This element helps remove moisture and dirt from the refrigerant, ensuring the air conditioning system continues to operate efficiently.
In the following image the A/C system is shown, with the condenser at the bottom. The refrigerant enters the condenser at a temperature of about 70°C and a pressure between 12 and 15 bar. Of course, this pressure and temperature vary depending on various factors, such as the air temperature, compressor speed and the amount of refrigerant in the system. When leaving the condenser, the refrigerant has a temperature of about 45°C and the pressure has slightly dropped to 11 to 14 bar. This decrease in temperature results in a corresponding decrease in pressure.
Cooling fans:
As soon as the air conditioning is switched on, the cooling fan for the condenser is also activated. Together with the driving wind, this cooling fan ensures that sufficient air flows through the condenser.
The number of fans differs per make and model of car. Sometimes there is one fan that serves both the radiator and the condenser, while in other cases one fan handles engine cooling and a separate, often smaller fan is used for the air conditioning (see image).
Possible malfunctions and defects:
When an air conditioning system is not functioning properly, the mechanic often first checks the pressures in the system. Depending on the fault, the condenser may be the culprit. These are the most common malfunctions and defects of the condenser:
- Leakage: One of the most common problems is leakage. This can be caused by corrosion, stone chipping or other damage to the condenser. The condenser is often mounted at the front, behind the front bumper and air grilles, making it easy for splashing stones to hit it. Leaking refrigerant can reduce the performance of the air conditioning system, eventually leading to a completely empty system. When all refrigerant has escaped and the pressures are too low, the compressor will no longer switch on for safety reasons.
When checking for leakage, we use a leak detector. When the system is filled with a UV additive, yellow/green stains can be seen around the leak. See the images below for a leak where refrigerant (1) and refrigerant + UV (2) are visible. - Narrowing or blockage: Contaminants such as dirt, insects or other material can obstruct the airflow through the condenser. The fins of the condenser can also be folded closed by objects from outside (stones), preventing air from flowing through, which leads to reduced cooling performance. By measuring the pressures and temperatures we can identify whether this is the case.
- Deformation or damage: Physical damage, such as bending or dents in the condenser, can reduce the efficiency of the heat transfer process. In the third image below, a damaged condenser can be seen.
- Malfunctioning cooling fan: The cooling fan for the condenser can be damaged or may fail to switch on due to an electrical fault. Especially without driving wind, the condenser is no longer able to cool the refrigerant.
- Corrosion: Exposure to moisture and road salt can cause corrosion, which affects the structure of the condenser and shortens its service life.
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