Helping your European vehicle navigate all sorts of tough terrain, an air ride system is one of the key reasons that manufacturers like BMW, Porsche and Mercedes are able to offer such unparalleled performance. These suspensions can do everything from keeping your tires in contact with any type of terrain and to actually being able to lower the vehicle to improve fuel efficiency and a vehicle’s handling. The air ride system works together with the drive train, hydraulic dampeners and electronic sway bars and at the center of these suspensions is an air compressor that provides the correct air volume and pressure needed by the corners. In these cars the compressor itself and the air ride control unit are intelligent components that communicate with the Body Control Module and the Stability Control Module on a serial date bus. These systems have their own dashboard light to indicate a malfunction but you will need a scanning tool to properly diagnose any system issues.
Just because you receive a failure code or a dashboard light won’t turn off doesn’t mean that there is a deeper issue, this can occur even if the issue is just that the air ride module is unable to communicate with the BCM. Using a factory diagnostic tool will be able to test the compressor directly as well as the valves and can save your hours of diagnostic time. This is another important aspect of maintenance as these extended wait times and the possibility of just throwing different parts at the issue to try and fix it can lead to expensive and frustrating repeated visits to the mechanics.
By monitoring the amount of time that the compressor runs, the Body Control Module is able to control the temperature of the compressor so it won’t damage itself trying to inflate a leaking bag or a stuck valve. Should the time exceed the set specification, the module could disable the compressor to save it or prevent any electrical issues.
As with most parts of a car, running the compressor for an extended period of time can lead to overheating which can in turn damage the diaphragm or a piston. A period of a compressor running too long can be caused if there is a leak in an air ride bag or a damaged line connecting them. Most of the time the more advanced systems will be able to recognize an issue like a damaged component and will take steps to alert the driver to the issue, these steps can include turning the dashboard light on.
The compressor requires clean and dry air to operate properly and when the system is damaged at all, it will begin to pull outside air that is contaminated and contains moisture as well. If air from a leak is entering the system it will be the equivalent of running the engine without using an air filter and can damage the compressor and also the valves. If there is no way to remove water from your system, then water will begin to corrode or freeze most or all parts of the system, in particular it can be damaging to the chamber that houses all of the compressor’s pistons.
The air ride systems typically have a dryer that is connected to the outlet that will absorb any water entering the system, usually it contains something like silica gel to help. The dryers will show when these gels and desiccants are full and additional desiccants can be added and installed in the supply line.
The compressor can overheat and wear out, which makes it the leading cause of damages to the air ride system. When it wears out, it can send debris and even oil to the rest of the air ride system. The oil and debris can degrade the air bellows even following a replacing of the compressor which is why flushing the lines is critical to do if a compressor has failed. The quality of the air supply is the most important part of maintaining the health of your air ride system and it’s a rare occurrence for just one part of an air suspension to fail. You can prevent issues by not only regularly maintaining and inspecting the air ride system with routine service appointments but also by responding immediately in the event your dashboard light should turn on.