[David and Teresa]

David,

The tank in the passenger drive wheel well has a check valve installed on top of it. The purpose of the check valve is to allow pressure from the 120V or engine compressor to flow into the feed for the slide seals, potties, and air doors BUT block the pressure from the 12V compressor from trying to fill all the suspension and brake air tanks. That check valve will chatter when air is flowing through it.

Does this happen when all air compressors are off?