The Adaptive Intelligent Ride Control, or AIRMATIC air suspension system in many Mercedes-Benz models provides quite the comfortable ride, but can include many of the hassles Mercedes owners face. The bulk of the AIRMATIC assembly includes an air compressor pump (located close to the front passenger side wheel well behind the front bumper), four air struts (one located behind each wheel), and a level control valve unit (sitting right above the compressor pump).
Air Strut Assemblies
Two major causes of failure occur with the air struts, one being a failed and ruptured bellow. Unlike majority of air suspensions, these cannot be checked with a solution of soapy water since the bellows are behind a protective alloy dust cover. Measuring the height at each corner multiple times over a 10-hour period, while not disturbing the vehicle, may alert you to this common problem. The second cause of failure are cracks or leaks developing on the top of the strut where the brass airline fitting connects, which is more prevalent in 2003 or earlier models. A soapy water solution can help you identify these leaks, and Mercedes does have repair kits available.
Compressor Pump, Relay and Fuse
Testing the AIRMATIC compressor pump can be as simple as listening to it while it’s running, or even raising the vehicle with the AIRMATIC Level Control Switch. If your Mercedes takes longer than 30 seconds to reach the raised height, or the pump is running louder than normal, you may have an issue with the compressor. Changing out the air filter on the compressor pump during regular intervals is also recommended. The AIRMATIC compressor relay is in location ‘O’ in the passenger side fuse box under the hood, and the F32 fuse is located with it, which also protects the AIRMATIC circuit. Check the fuse with a quality multimeter on continuity, and always replace your relay when you replace the compressor pump.
Level Control Valve
The Level Control Valve or Ride Control Valve Block delivers the air from the compressor to each air strut which has four solenoids and a pressure sensor built in. The high-pressure line coming from the compressor pump is known to be a failure point, and a solution of soapy water can be an easy test for the valve block for any leaks.
Other Known Issues
The AIRMATIC Central Reservoir, located behind the bumper in front of the driver side wheel well is rarely a cause of issues in the W220, however should be checked during routine maintenance. Three level sensors monitor the vehicle’s height, two located at the front control arms and one on the rear axle. A dealer or mechanic with a STAR diagnostic tool will be able to run an automated test on the reservoir, level sensors and other components of your AIRMATIC system.
What We Offer
Suncore Industries carries a full line of new and remanufactured replacement parts for the W220. Complete conversion kits are also available for those that no longer want air suspension and prefer standard struts & coil spring suspension. In addition, there is always someone here at Suncore to receive your call without having to require you to go through an automated menu. We are here to answer any questions you may have!