It may be that the tension on the belt is to high. Usually about 1/2" is good. With serpentines you don't have much choice though. So as long as the tensioner is working properly , you can rule that out.
Has the idler wheel been replaced? It may also be that the belt needs time to stretch and break in. Sometimes belts just suqeal until they get warm. It is usually indicitave of a loose belt slipping across a pulley. You have so many new parts that are all breaking in I would give it some time as they will spin more freely once they have some miles on them.

Answered by DrCranknWrench (expert)
3,292 answers provided

well i dowt its the new parts getting brokenn in because i got them off of another eclipse at a used parts store so the have been brokin in im sure. im not sure what u mean by the tension on the bet is to high? and ughm idler wheel?

Response from simmons1332
1 question asked

See if a ther is a spacer on one of the tensioner that's in the wrong place

Answered by djcl (expert)
788 answers provided