96 Tahoe weird noise from blower fan

I have a weird and very annoying noise coming from my blower fan. I can only hear it on the first 3 settings, but i don't know for sure what it is. I haven't had time to tear it apart yet. I figured i would check here first. Any ideas would be great.

If it sounds like a high pitch squeal, steady but sometimes fades away and comes back, it means your bearing are going out in the fan motor, sometimes a light oil will help it, then again, some fans are sealed and cannot be oiled. Once you oil em, they will squeal again, only louder...the best solution is to replace it with a new one....