When diagnosing a faulty air conditioning system in a car, pay special attention to the condition of the air conditioning condenser (air conditioning cooler). These parts work in difficult conditions, because there are high pressures and variable operating temperatures.
The condensers, due to their location at the front of the car, are exposed to stone impacts from the wheels of other cars, as well as to salt and sand on the roads in winter (especially when driving fast on the highway). The condenser is also exposed to chemicals in car washes, especially in the case of trucks, where the condenser is located directly, in a very short distance behind the "grill" of the car. All this means that in a car that is already several years old, the air conditioning radiator may be heavily corroded and may have bent louvers from mechanical impacts, and thus it does not give off heat as intended by the designer, increasing the load on the air conditioning system.
Basic types of air conditioning condensersThere are two basic design solutions for condensers: parallel flow condensers, which are a newer design solution, in which individual batches of tubes are connected in tubular collectors with intermediate chambers, collecting the refrigerant, which moves in the condenser between several sections of tubes the other side, and series condensers that have one long tube ("serpentine") that conducts the refrigerant from the inlet to the outlet of the condenser.
Due to the location and the delicate, openwork structure of the condensers, these elements are naturally subject to operational wear. Due to the fact that the working medium works under high pressure in the air conditioning system, the refrigerant leaks through the condenser very quickly and occurs even through its smallest cracks, punched holes or corrosion pits. Corroded and bent condenser louvres no longer dissipate heat energy taken from the car cabin as efficiently. This makes it necessary to operate the compressor at higher pressures, which means a greater load on the compressor - points out Artur Gołembniak from Chłodnice Nissens Polska Sp. z o. o. Remember to gently clean the aluminum fins of the condenser from dust and dirt that accumulates while driving - this will allow you to maintain its efficiency. A corroded and oxidized condenser with broken louvers is generally not suitable for welding and repair, but for replacement with a new one.
Many companies that service air conditioning systems face this issue. In general, the need to replace the condenser depends on its construction. If the condenser gets dirt and filings delivered with the refrigerant from the seized compressor, it is necessary to first try to rinse them out of the condenser to exclude the possibility of reintroducing the contamination into the system. However, rinsing with specialized fluids and a rinsing machine is a reasonably effective solution only for condensers built in series, i.e. equipped with one serpentine-shaped tube that directly connects the inlet to the outlet of the condenser. However, rinsing is ineffective in the case of parallel-flow air conditioning coolers, having a multi-tube structure, with very small cross-sections of conductive channels, where individual parallel tubes fall into intermediate chambers, from which it is very difficult to flush out impurities. At the moment, it can be said that parallel condensers are common in vehicles and that they have replaced series condensers. Parallel condensers are light and efficient, but the large number of intermediate chambers used unfortunately favors the deposition of impurities in them, which are difficult to remove by rinsing - the only really effective solution is to replace such a condenser with a new one, notes the Nissens representative. Therefore, especially in the case of compressor seizure, if there is a condenser with a parallel design in the air conditioning system, it is recommended to replace the condenser with a new one before installing a new compressor. The use of an old condenser after the A/C compressor seizes may cause swarf to enter the system, which may cause blockage of the expansion valve or expansion nozzle and damage to the new compressor.
An indispensable element that works with the condenser is the dryer, otherwise known as the air conditioning filter, which is often factory-integrated with the condenser. Moisture that gets in if there is a leak or opening of the system, replacement of the condenser or seizure of the compressor. system and causes the formation of corrosive acids, it is absorbed by the hygroscopic agent that is filled with the dryer. Due to its small volume, the dehumidifier has a limited absorption capacity. Note that the dryer should be replaced every time there is a leak or open in the system, replacement of the condenser or seizure of the compressor. 
