How do you replace heater core in 1999 e 150 ford van?

To replace the heater core in a 1999 Ford E-150 van, begin by disconnecting the negative battery cable and draining the coolant. Next, remove the dashboard components, including the center console, to access the heater core housing. Detach the hoses connected to the heater core, then unbolt and remove the heater core from the housing. Install the new heater core, reassemble the components, and refill the coolant before reconnecting the battery.