AC servicing advice from Nissens
A receiver drier
Components provider Nissens Automotive has highlighted the importance of workshops undertaking thorough assessments of CV air conditioning systems, to ensure that they operate efficiently and that working life is maximised.
“One of the key assessments to ensure the AC system’s reliability and effectiveness, is the purity of the oil/refrigerant mixture,” said Nissens Automotive’s marketing manager, Jan Zieleskiewicz.
“So, rather than just thinking of the gas pressure as the weather improves, it is sensible for workshops to periodically perform a system inspection and, among other checks, this should include an inspection of the cleanliness of the AC loop.
“The AC circuit’s inner condition can tell a lot about potential problems within the system and deterioration of the medium mixture provides an excellent indication when making this assessment,” Zieleskiewicz continued.
“Furthermore, the only way to determine the correct lubricant quantity in the system, as well as to secure the purity needed for its proper operation, is by flushing out the old mixture and replenishing it with fresh oil and refrigerant. Additionally, whenever replacing one of the system’s key components, such as a condenser or compressor, flushing is crucial to ensure a complete and effective repair.”
Nissens, which provides premium replacement components for AC systems as well as technical support and advice to CV service and repair providers, points out that the refrigerant and lubricant necessary for the system’s vital operation can get contaminated by substances such as moisture, particle formation due to uncontrolled chemical reactions, or careless use of additives including UV dye or leak-stop agents.
These can easily cause clogs in the narrow channels within the system, the company says, leading to consequential severe failures, so flushing the system is vital.
“There are three recommended ways to flush the AC system, but there also some basic rules that have to be observed to do it successfully,” says Zieleskiewicz.
“First, irrespective of whether the AC compressor is being replaced, it must be separated or bypassed when the flushing process is carried out, likewise the system’s expansion devices, such as the orifice tube or expansion valve, and the receiver drier or ‘desiccant’ should be removed and replaced after flushing.
“It’s also worth pointing out that parallel-flow, thin and micro-tube condensers, as well as evaporators, cannot be flushed effectively and should be replaced or back flushed whenever serious contaminants have impaired the system or following a previous compressor seizure.
Micro-tube condensers
“When it comes to the flushing, the preferred method will largely depend on the equipment and extra tools that the workshop has access to, but it must be effective and should not harm the system, which might be the case if an improper method was to be followed.
“Also bear in mind that, with whichever method, cleaning agent residues must be completely removed after flushing and the AC loop must always be thoroughly dried, preferably by means of nitrogen and a long-process vacuum.”
Nissens outlines the three methods below.
Method one: Using a dedicated flushing detergent
Based upon circulating the detergent throughout the loop and injecting it directly from a pressure container or distributing it by a special flushing machine, this method dissolves all sorts of particles, sludge, stubborn soil, and residues.
This method can easily combine with highly pressurised nitrogen to ‘push’ the flushing agent through the ducts, but ideally, the loop segments should be flushed separately. This method has proven effectiveness against stubborn soiling and, besides assisting the flushing agent, the nitrogen is very effective at moisture removal.
Method two: Refrigerant and filling station
This option uses the R134A/R1234yf refrigerant circulated around the AC loop by the means of an AC filling station. However, the filling station must be equipped with a flushing function, specially designed filters and a container to catch the contaminants. This method is good at cleaning loose particles, but isn’t very effective at rinsing out serious sludge and soils.
Method three: Refrigerant directly from bottle
This again uses the R134A/R1234yf refrigerant as the cleansing agent, but relies upon the adapter set and hoses having a tight leak-free connection. The refrigerant is circulated through the loop by heating up the bottle, but an additional bottle for contaminated gas must also be prepared.
This method has the advantage that it does not require any additional agents or an AC filling machine, and is effective at cleaning loose particles, but isn’t very effective for rinsing serious sludge and soils.
A Nissens inspection tool
Zieleskiewicz continued: “Once the AC system is properly flushed, and all of the necessary components have been replaced, technicians can proceed to inspect the system to ensure the joints are tight and there are no leaks, and then charge the system using the vehicle manufacturer’s prescribed specification and quantity of refrigerant and lubricant.”
Further information on AC system flushing, as well as a wide range of additional technical resources, can be found at Nissens’ support portal (support.nissens.com).
More information on Nissens’ aftermarket range can be found at the URL below.
