Replaced serpentine belt at suggestion from service tech; belt worn and beginning to crack. No other signs that belt was in need of being replaced. Replaced belt-horrible squealing upon starting ignition. Could not use air conditioner or defrost. Service tech adjusted tension on belt and used belt dressing; it improved a bit. Two days later, same problem. Service tech has made adjustments several times and even replaced belt. Same problem. Took Jeep to a mechanic who replaced belt with so-called better belt. Worse than even before. Suggestions have been that it could be the compressor or water pump going out, idler arm pulley and/or various other pulleys. I cannot understand it being the compressor as the squealing is immediate and loud upon starting Jeep and compressor not running. Any ideas? Running out of mechanics at this point, and getting to be a rather expensive ordeal.