What causes a cold-start squeal from serpentine belt, tensioner or accessory?

[Layla_W]

I’ve got a persistent squeal from my serpentine belt area that only happens when the engine is cold. I’ve checked the belt itself for cracks and it looks okay, but the noise is really embarrassing on morning starts. I’m wondering if it’s the belt tensioner pulley starting to fail or if one of the accessories is causing the drag.

[Alexander79]

Had a morning squeal in the serpentine belt area too. It showed up only when the engine was cold. I checked the belt itself—no cracks—and then swapped it for a new one. Noise dropped a lot after a few drives, but the tensioner pulleys still felt a little stiff for the first few starts.

[George85]

I kept thinking it was the belt, but I suspect the bearings in the tensioner or the idler. On cold starts, the bearing would drag a bit and the squeal would fade once it warmed up.

[VioletIL]

One time I chased it to the alternator; the pulley side seemed fine but the alternator was dragging when cold. Replacing the alternator solved it, but that was an expensive detour.

[Aurora_M]

Do you think the real issue is the belt or could something else be dragging after a cold start? I keep second guessing myself.