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Condenser

Subjects:

  • Condenser
  • Cooling fans
  • Possible malfunctions and defects

Condenser:
The condenser has an important function in a car's air conditioning system. The refrigerant gives off heat here and changes from gas to liquid.

From the air conditioning pump, the refrigerant enters the condenser in the form of superheated vapour. This is because the refrigerant has absorbed a lot of heat while cooling the air in the car. In the condenser, the refrigerant is cooled and its temperature drops below its boiling point. This turns it 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. Like the radiator, the condenser acts as a heat exchanger. It consists of curved tubes in a kind of serpentine arrangement, through which the driving wind or air from fans can flow. In some vehicles we find condensers that are cooled with water.

In the figure below, the refrigerant inlet is at the top left and the outlet is at the bottom right. The “filter / drier element” can be placed next to or on the condenser. This element helps to remove moisture and dirt from the refrigerant, keeping the air conditioning system operating efficiently.

The following figure shows the air conditioning system, 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 will vary depending on various factors, such as the air temperature, the speed of the compressor and the amount of refrigerant in the system. On leaving the condenser, the refrigerant has a temperature of approximately 45°C and the pressure has dropped slightly to 11 to 14 bar. This decrease in temperature causes a corresponding decrease in pressure.

Cooling fans:
When the air conditioning is turned 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 car make and model. Sometimes there is one fan serving both the radiator and the condenser, while in other cases one fan provides engine cooling and a separate, often smaller fan is used for the air conditioning (see picture).

Possible malfunctions and defects:
When an air conditioner is not functioning properly, the technician often first checks the pressures in the system. Depending on the malfunction, the condenser may be to blame. Here are the most common condenser failures and defects:

  • Leakage: One of the most common problems is leakage. This can be caused by corrosion, stone chips or other damage to the condenser. The condenser is often located in the front, behind the front bumper and air vents, so that flying stones can easily collide with it. Leaking refrigerant can reduce the performance of the air conditioning system, resulting in a completely empty system. When all refrigerant has escaped and the pressures are too low, the compressor no longer switches on for safety reasons.
    When checking for leaks, we use a leak detector. When the installation is filled with a UV additive, yellow/green spots are visible around the leak. See the images below for a leak where refrigerant (1) and refrigerant + UV (2) are visible.
  • Constriction or Blockage: Contaminants such as dirt, insects or other material may restrict the airflow through the condenser. Also, the fins of the condenser can collapse due to external objects (stones), preventing the air from flowing through them, which leads to reduced cooling performance. By measuring the pressures and temperatures, we can recognize 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. The third image below shows a damaged condenser.
  • Malfunctioning cooling fan: The cooling fan for the condenser may become damaged or may not turn 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 salt on the road can cause corrosion, which affects the structure of the condenser and shortens its life.
Leakage (1)
Leakage (2)
Bent slats