How do you replace an ac evaporator on a 1999 Buick Century?

To replace the AC evaporator on a 1999 Buick Century, first, disconnect the battery and relieve the refrigerant pressure. Remove the dashboard and the center console to access the HVAC housing. After removing the housing, disconnect the evaporator from the refrigerant lines, and replace it with the new unit. Finally, reassemble the HVAC housing, reconnect the refrigerant lines, recharge the system with refrigerant, and test the AC for proper operation.