Broken Heater Belt

I've got a feeling that a belt in my heater broke, it started sqeeking and then it started rattling and now if I turn the fan up it makes a horrible flapping noise.

I searched for heater belt on the tech forum but didn't come up with anything.

Does anyone have relatively simple instructions on how to replace the belt? I'm going to look around for a Hayes manaul today and see if it's something that my dad & I can work on this weekend.

It's an '84 190E four cyl with AC.

I just spent $600 for a new catalytic converter, exhaust pipe and muffler this weekend and today I'm replacing the spark plug wires, obviously my budget is shot right now and if I can do it cheaper myself, then I'll be really happy.

But something in my gut tells me this is going to be harder than I think.

Liz