With much interest I read where some members are having problems with a/c belts and bolts shearing off.   Recently, while I had the engine cover open, with the engine running, I noticed the a/c compressor moving around.   Upon further investigation I found the compressor firmly tightened to a thick steel plate (about an inch thick), but this plate was loose.   I had to remove the compressor to access these bolts that hold these plates and these bolts were loose.   I put on some blue Loctite - so far so good.   Maybe this will help someone.   I have a 99 E with a 5.  9 Cummins 275.   Steve Harry

Since Steve sent us this note, quite a few D owners with the ISB engine have experienced this problem - sometimes with disasterous results, as the compressor can fall off into the fan, which then damages the radiator.   Unfortunately, you cannot just wiggle your compressor to determine if you have a problem - you have to completely remove the compressor.   Cummins is working on a solution.