problem in changing serpentine belt of my I4 alero

Yesterday, I am trying change serpentine belt on my I4 alero (2000). I found it is easy to uninstall old belt. But it is very hard to put the new one, since the new belt is much shorter than old one. I suspect the Autozone guy give me a wrong one. The new belt is made by duralast. Anyone can give me advices?

Second question: I also want to replace A/C blower resistor. But I found the bacl bolt is hard to reach using my socket and wrench.

The new belt may be marginally shorter than the old since the old one has probably stretched, but it shouldn't be much shorter. It can take a bit of wrestling to get them on. If the new belt seems more than an inch or so shorter, take the old belt and the new belt back to the store and have them check the part number - they may have grabbed the wrong one.

The blower motor resistor can be tricky - just replaced mine about a month ago. I found it easiest to remove the blower motor (three bolts), and that gave me a bit more room to work. There isn't much advice for the bolt closest to the firewall except to get a 7/32" socket on it, might need a swivel, and just keep working at it. It'll come out eventually.

Just checked online, and the belt for your car should be Duralast 475K5. That's the belt listed for a 2000 Alero with a 2.4, with or without AC. Don't think there are any non AC alero's out there, at least that I've seen.

Does the belt tensioner move freely?