mazda breaking belts

i have a 1998 mazda millenia, when you run the air conditioner it breaks the belt,sometimes it breaks the harmonic balencer,i know the compressor is probably locking up, is this something i can change myself or do i need to get a professional.

Yes you can change it your self, but you will have to get it re gased, you shouldnt conect the belt to it until it has gas though, but fitting it your self will save you some money. re gasing will cost $40-$50 Au

Yeah you can change it yourself, but I would take it to an shop to have it discharged before you unhook the line, then have it recharged like said above.

If he pays to have the system drained and pays to have it refilled, how much money will he save by switching out the compressor on his own?

Most shops charge around $45/hr labor, it would probably take two hours to change out that compressor.