I also have KIA Sephia 2001. i have the problem of trying to quiet the belt squealing and i replaced the belts all three and replaced the water pump... still squealing. next step would be to take them off and do one at the time... i think the alt belt on first make sure that one don't make any noise then put on the ac belt make sure its quiet... I tried every thing you guys have discussed.I think isolating one belt at a time should work . fingers crossed