May 2021

34 AFTERMARKET MAY 2021 AIR CONDITIONING www.aftermarketonline.net aftermarket perspective,” said DENSO Europe Pan European Strategic Marketing Manager Fatiha Laauich, “the compressor is one of the components that has the highest rates of failure.” “The number one cause of replacement compressor failure is due to dirt that is left in the system when the new compressor is fitted. By checking the suction and discharge ports and draining the old oil from the failed compressor, it is easy to determine if a system is dirty or not. If it is evident in these areas, the system needs to be flushed and all the necessary parts needs to be replaced, before the new compressor is fitted. Some parts, like multi-flow condensers, expansion valves or receiver-driers, cannot be flushed, so if dirt is found, these components should automatically be replaced, along with the compressor. “The use of a non-authorised chemical, or the failure to remove chemical residue before refilling the A/C system with fresh oil and refrigerant, is the second biggest cause of failure. The main culprit is flushing agent, which if left in the system, dilutes the compressor oil making it unable to provide sufficient lubrication, causing the compressor to fail. Likewise, if too much UV dye is introduced into the circuit, the viscosity and performance of the oil is reduced. On the other side of the equation, DENSO does not recommend the use of chemicals for flushing or servicing A/C systems, as it usually creates more problems than it will solve. “The third most common failure is liquid lock, caused either when there is too much oil or too much liquid refrigerant on top of the pistons in the compressor, making it unable to rotate, and locking it. This can cause the limiter in the drive pulley to break or, if it has a magnetic clutch, to burn out. “Lubrication issues are the fourth most common reason for failure, either due to a lack of oil or a blockage in the A/C system, which generally result in compressor seizure. The first indication that a lack of oil has caused the failure comes if only a small amount is present when the compressor is drained, whereas if the suction port is clean and dry, a blockage is the likely reason. “The final cause in the top five, relates to the compressor’s drive system, which, in common with liquid lock can result in the limiter in the drive pulley breaking. This kind of pulley failure can be as a result of the alternator free-wheel pulley seizing and subjecting massive strain on the auxiliary belt and subsequently the compressor pulley, engine torque fluctuations from rough idle/running, excessive torque from engine chip tuning/remapping, engine vibrations caused by a defective crankshaft damper pulley, a faulty auxiliary belt tensioner, a lack of lubrication within the compressor increasing its resistance, vibrations resulting from a broken dual mass flywheel, or finally, vacuum lock. Vacuum lock is relatively rare and is caused when the A/C system in a vehicle fitted with a variable displacement type compressor is under vacuum, and the engine is accidentally started. In this instance, due to centrifugal force, the compressor’s pistons hit against the crank chamber wall, locking it. “ Best protection Commenting on the important role played by filters in the A/C equation, UFI Filters’ Karl Ridings, Sales Director UK & Ireland – Aftermarket observed: “The standard rule of thumb for cabin air filter replacement to be carried out is once a year, but it should be done at even shorter intervals in areas that are particularly dusty. Although the concentration of dust in the atmosphere and the presence of various harmful particles such as PM10 and PM2.5 varies with weather conditions and geographic location, levels inside the vehicle can be as high as six times the outdoor level. This is due to the tunnel effect created by the ventilation circuit.” Commenting on changes in the way filters are made and function, Karl said: “In the past, there were mainly two kinds of cabin air filters – anti-pollen filters and active carbon filters. Recently, the manufacturers have extended these product groups with more effective solutions that are designed to block and destroy bacteria even more efficiently. Internal tests have shown that these solutions, however, tend to deteriorate within only a few working cycles after installation. UFI ARGENTIUM is a different concept featuring distinct blue fibres and a special fabric structure which incorporates silver particles with powerful antimicrobial characteristics. It maintains its ability to neutralise bacteria, fungi and mould, reducing the bacterial load by over 99% throughout the filter’s entire lifetime. The Innovative ARGENTIUM filtering media is composed of three layers to stop pollen, dirt, tyre-wear dust, fungi, and bacteria, while absorbing SO2 and NOx. Thanks to the presence of active carbon, the media material also guarantees a filtration efficiency that exceeds 98.5% for particles with a diameter of 2.5 microns as well as eliminating harmful gases and unpleasant odours. The filter is fully compliant with the ISO 11155-1 standard.”