How do you change a evaporator core on a 2000 Chevy Express van?

To change the evaporator core on a 2000 Chevy Express van, first, disconnect the battery and drain the coolant. Remove the dashboard and HVAC assembly to access the evaporator core, which is typically located behind the dashboard. Unclip and detach any hoses connected to the core, then remove the core from its housing. Install the new evaporator core, reassemble the HVAC system, and refill the coolant before reconnecting the battery.