Condenser:
The condenser plays a crucial role in a car’s air conditioning system. The refrigerant releases heat here and changes from gas to liquid.
From the AC compressor, the refrigerant enters the condenser as an overheated vapor. This occurs because the refrigerant has absorbed a lot of heat while cooling the air inside the car. In the condenser, the refrigerant cools down and lowers 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 vehicle, in front of the radiator. Like the radiator, the condenser functions as a heat exchanger. It consists of bent tubes in a kind of winding arrangement, allowing the airstream or fan air to flow through. In some vehicles, we find water-cooled condensers.
In the image below, the refrigerant inlet is located at the top left and the outlet at the bottom right. The “filter / dryer 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 AC system is depicted, with the condenser at the bottom. The refrigerant enters the condenser at a temperature of approximately 70B0C and a pressure between 12 and 15 bar. Of course, these pressure and temperature levels vary depending on various factors, such as ambient air temperature, the compressor’s RPM, and the amount of refrigerant in the system. Upon leaving the condenser, the refrigerant has a temperature of approximately 45B0C and the pressure has slightly dropped to 11 to 14 bar. This temperature decrease results in a corresponding pressure drop.
Cooling Fans:
Once the air conditioning is switched on, the cooling fan for the condenser is also activated. Together with the airflow, this cooling fan ensures there is sufficient air flowing through the condenser.
The number of fans varies per car brand and model. Sometimes there is one fan serving both the radiator and condenser, whereas 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 technician often checks the system pressures first. Depending on the malfunction, the condenser could be to blame. These are the most common malfunctions and defects in the condenser:
- Leakage: A very common issue is leakage. This can occur due to corrosion, stone chips, or other damage to the condenser. The condenser is often mounted at the front, behind the front bumper and air vents, making it easy for flying debris to hit it. Leaking refrigerant can reduce the air conditioning system’s performance, eventually leading to a completely empty system. When all the refrigerant has escaped and the pressures are too low, the compressor will not engage for safety reasons.
When checking for leaks, a leak detector is used. When the system is filled with a UV additive, yellow/green spots can be seen around the leak. See the images below for a leak where refrigerant (1) and refrigerant + UV (2) are visible. - Restriction or Blockage: Contaminants such as dirt, insects, or other material can obstruct airflow through the condenser. Additionally, the fins of the condenser can be folded shut by external objects (such as stones), preventing air from flowing through, which leads to reduced cooling performance. We can recognize this by measuring pressures and temperatures.
- Deformation or Damage: Physical damage, such as bending or dents in the condenser, can decrease the efficiency of the heat transfer process. In the third image below, a damaged condenser is shown.
- Faulty Cooling Fan: The cooling fan for the condenser can become damaged or may not activate due to an electrical fault. Without airflow, the condenser cannot cool the refrigerant.
- Corrosion: Exposure to moisture and road salt can cause corrosion, which affects the structure of the condenser and shortens its lifespan.
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