When we bought our DSDP new in 05 the a/c units were nice and quiet. When the rear unit failed we had a new Dometic installed and it sounded like a helo was landing on the roof. Many hours of attempting to quiet it down has been unsuccessful. One thing I did notice when I pulled the cover was most of the parts are now plastic. The old unit was mostly aluminum but the new units are plastic and not very sturdy plastic at that. It shakes and rattles to no end. Over time I have gotten used to it but the quality is less than superior. Even the foam lining is like thin paper and degrades quickly. I guess it's all about making a profit not a quality part.