The brief
The GLC43 had started sitting unevenly, one corner of the front lower than it should be, and the ride had gone harsh and unsettled, the body floating and crashing over bumps instead of staying composed. He brought it in. That car runs air suspension at the front, where an air strut replaces the conventional spring-and-damper, holding the ride height with air pressure and controlling the body with an adaptive damper inside. When a front strut fails, it can't hold its air, so the corner sags and the ride height goes uneven, and the damping goes off so the front floats and crashes. On a performance SUV like this you want the front planted, and a failed air strut only gets worse, so it isn't something to drive on.
The diagnosis
On the lift the front air struts were checked, and the affected side was losing air and the damping was past spec, with the other side tired but not yet leaking. The air supply, the compressor and the lines checked out, so the struts themselves were the fault, not the system feeding them. With one leaking and the other worn, the call was to do the front pair, struts work as a pair across an axle and a mismatch leaves the front handling unevenly, so it was a matched set, with the ride height recalibrated after.
The work
Both front air struts came off, and a matched pair of genuine Mercedes-spec air struts went on, the air lines reconnected, the mounts torqued to the manual figures, and the system bled and the ride height recalibrated to spec. A road test confirmed the car sat level, the ride was settled, and the front stayed planted over bumps and through corners.
The outcome
The car sitting level, a settled, composed ride, and the front planted again over bumps and through corners. The GLC43 went home with the front suspension back to how it should drive. Air struts wear together and they take the car's stance and composure down with them, so a fresh matched pair and a recalibrated ride height brought the front back to spec.