How do you replace and change an expansion valve on a 1998 sl1 Saturn?

To replace the expansion valve on a 1998 Saturn SL1, first, ensure the AC system is properly evacuated to remove refrigerant. Remove the dashboard and the HVAC unit to access the expansion valve, typically located in the evaporator case. Disconnect the old valve from the refrigerant lines, install the new valve, and reassemble the HVAC unit. Finally, recharge the AC system with refrigerant and check for leaks.