Customer may hear squeaking or beeping noises from front of vehicle when driving on uneven roads after a stationary period. This condition occurs on vehicles with air suspension (PR-1BK) if the damper was very warm when the engine was switched off. The noise disappears as the damper warms up, after compressing once or twice. Bubbles are created in the oil because of temperature fluctuations, particles, and high oil flow speed. The bubbles gather around the damping adjustment valve when the engine is switched off. When the vehicle is started again, the cold oil prevents the bubbles from being dispersed quickly, which reduces the hydraulic damping. The reduced hydraulic damping causes the armature in the damper to vibrate, which creates squeaking noises.
As soon as the bubbles have been dispersed, the hydraulic damping works fully and the noise disappears.