Squelching belt problems

[rks171]

After about 70 k miles, my belt started screeching, so I changed it. It was quiet for maybe 10 k miles, then slowly started screeching again. I ended up changing it again around 110 k. This new one is not screeching, but it's more of an intermittent squealing sound. Normally, I have the heat and blower on due to the time of the year. I have found that if I turn the blower off, the squealing slows down and stops. It does this weather the defrost is on or not.

Now, when it makes the squealing sound, I can hear the blower kick down, like it's losing power. When the squealing stops, it resumes its normal frequency. I'm guessing the belt is slipping and reducing the power output of the alternator, which is why the sound change.

I'm starting to think this is not a problem with the belt, but with a component on the belt. Maybe a bearing is going and when the bad component starts grinding, it's making the belt slip and reduce power output of the alternator.

So what are all the components on there? I see the engine, the alternator, and two other things. Is that the water pump on the bottom?

Another possibly related problem is that when I come to a stop or coast while idling (not hitting the accelerator), I car sometimes vibrates violently, sounding as if it's going to stall.

I'm thinking it might be a bearing going on one of the components, but would greatly appreciate any of your feedback or suggestions for testing and finding the root of the problem as I'm no professional mechanic.