Air suspensions of one type or another have been used on a variety of makes and models over the years. The advantages of having a vehicle on air rather than spring steel are (1) smoother ride, (2) ride stiffness adjustability, and (3) ride height adjustability (automatic load leveling).
Air suspensions are typically found in luxury nameplates such as Audi, Bentley, BMW, Buick, Cadillac, Hummer, Jaguar, Land Rover, Lexus, Lincoln, Mercedes-Benz and Porsche, and also Chevrolet, Ford, GMC, Oldsmobile, Pontiac, Saab and Volkswagen. Some of these suspensions date back to the 1980s. Although many of these older vehicles are no longer on the road, there are still a lot of aging vehicles with air suspensions that are in need of repair.
The typical failures on these vehicles include air leaks in the air springs, lines or plumbing, compressors that no longer work, and valve, height sensor and control issues.
Compressor failure are often the result of an ongoing and undetected air leak. The compressors in these systems are not designed to run continuously, but to add make-up air as needed when the suspension self-levels. When a leak occurs in a spring or the air line plumbing, it forces the pump to cycle more frequently. And the worse the air leak, the more the pump has to run to offset the loss of air. Eventually, the pump runs so much that it overheats and fails. The suspension goes flat and the vehicle owner has a major problem that needs to be fixed. Replacing the failed air compressor may seem to be the correct repair for the problem, but in most cases the underlying cause is an air leak that must be found and repaired before the new compressor is installed.
Rubber is an amazing material that provides both elasticity and flexibility. But as rubber ages, it tends to stiffen and crack. Consequently, those the air bladders inside new air springs, air shocks and air struts eventually develop cracks and pinhole leaks by the time they are six to 10 years old — even on low mileage vehicles. The same thing can happen in flexible plastic air supply lines that route air from the compressor to the springs, shocks or struts.
Original equipment air springs, air shocks and air struts are typically very expensive to replace. They can also be difficult or impossible to find for older applications if the vehicle manufacturer has discontinued the parts in the dealer network. The only option at that point is to go with aftermarket replacement parts, or to convert the air suspension to a convention suspension with a conversion kit (where available).