If the AC compressor pulley is turning free, it won't affect the serpentine belt. If that pulley is locked up, you need to fix it, or bypass it (and bypassing it can cost nearly as much as fixing it). The AC pulley does not directly drive the AC compressor, it is clutch driven, so it's possible for pulley to turn freely even if the compressor is locked up. All other pulleys directly drive their components, such as power steering and alternator. If either of those pulleys are locked up, you need to fix them. With the belt off, you should be able to turn all pulleys freely by hand, including tensioner and idler pulleys. If not, then they will interfere with operation of serpentine belt.