Many misconceptions persist in the industry, and one of those is that air conditioning service and maintenance is only necessary in the spring and summer. However, regular inspection of the system is important throughout the year. Nissens explains.
Although many owners only associate A/C as a means of keeping cool when the weather is hot, workshops need to remind them that the system also dries humid air coming in to ventilate the cabin, so it is the quickest and most effective way to reduce condensation inside the vehicle and prevent the windows from fogging up, whatever the time of year.
In addition, using the A/C regularly keeps the oil/refrigerant mixture moving through the system, which ensures its internal components remain sufficiently lubricated. So, using it all year round is the best and safest option, and in modern applications such as plug-in or hybrid vehicles with heat pump systems, it’s the only one!
As a result, A/C system repair and maintenance should be important to independent workshops, whatever the season and Nissens Automotive is on hand to provide them with the technical advice and replacement components they need to make it so.
Naturally, there are many components within the system, but the condenser is a very important element, and its correct operation is vital because a faulty condenser, even if it is still partially working, can lead to severe A/C problems and sometimes result in damage to, or even seizure of, the compressor. Compressors are very expensive and replacing one will take the vehicle off the road as the rest of the system will need to be examined, flushed and charged with new refrigerant and lubricant, making it an even more costly experience for owners.
The condenser is typically attached to other heat exchangers in the engine compartment and its role is to ensure that the state of the refrigerant changes from gas to liquid, which happens through condensation. The airflow through the condenser’s fins enables this process by extracting the refrigerant’s heat and exchanging it with the ambient air.
So, what should technicians look out for when servicing the A/C system?
Mechanical damage
This problem is often ruled out as a reason for reduced system performance or compressor failure, because leaks and surface perforations are generally considered the most common causes for system failure. However, even light mechanical deformation of the condenser tubes and fins can have a big effect because just one deformed condenser tube can restrict refrigerant flow inside the unit, significantly reducing the system’s performance. Furthermore, the limited flow will cause abnormally high pressures and temperatures in the loop, increasing the workload on the compressor and effectively reducing its lifespan.
Corrosion
As one of the A/C system’s components that is placed closest to the external environment, the condenser is constantly exposed to hostile conditions from the elements, with heavy rain, snow and humidity being particularly damaging. But when the roads are covered by salt during the colder months, saltwater spray exposes it to the increasing risk of corrosion. Even if the condenser doesn’t leak and its joints seems tight, its heat exchange capacity can operate at a much lower capacity as this corrosion attacks the thin aluminium fins, reducing the working surface area and consequently decreasing its overall heat exchange capacity. Deterioration of just one fin row can reduce thermal performance by up to 5 per cent!
Blockages
When impurities develop in the system, the thin channels of the condenser will quickly clog up. This can restrict the refrigerant flow, eventually reducing the unit’s ability to exchange heat. In most cases, this will subsequently cause overpressure in the system, which is very harmful to the compressor. Condensers with micro and nanotube technology are at significant risk because, while micro tube technology offers outstanding cooling performance, the thin tubes are more prone to blockages. Among the main causes are internal contamination, improper system flushing, overdosing system additives, and degraded lubricant. However, a defective receiver-drier is another common culprit.
Condenser best practice
Always handle the condenser properly and do not ignore any light damage on its surface. If the tubes or fins are visibly damaged, replace the condenser with a new unit.
Irrespective of the primary reason why a vehicle visits the workshop, technicians should always carry out a visual inspection of the entire A/C system looking for leaks and oil residue on component surfaces, around joints and at couplings.
Thorough inspection of the condenser’s surface can save expensive system and compressor repairs, so any sign of corrosion or leaks must be considered as serious threats to the efficiency and operation of the system. Pay particular attention to the bottom part of the condenser, where tubes and fins are particularly exposed to humidity and aggressive salt spray and if any signs of leakage or missing/deteriorated fins can be seen, replace the condenser.
When replacing condensers, choose one with corrosion protection applied, as this will considerably prolong its lifespan. To keep the condenser in good condition, the receiver-drier must always be replaced during a compressor replacement if the circuit has been exposed to ambient air, or the system has run empty due to leaks.
Perform a system flush after a compressor breakdown and make sure that no flushing agent residues remain in the system afterwards. Always use the recommended oil and additives and replace the condenser in case of doubt.
