1 - Drain approximately two quarts or more of coolant from the radiator. I usually just drain the whole radiator since I'm probably due for a coolant change anyhow.
2 - Disconnect the heater hoses, might be a good time to replace them with new.
3 - Disconnect damper door control cables.
4 - Disconect blower motor wire, usually located in the engine compartment, on the firewall, below the battery tray.
6 - Remove nuts from heater housing studs, located on the firewall in the engine compartment.
7 - Remove heater housing assembly by tilting down to disengage from air inlet duct and pulling to the rear of the vehicle.
8 - Remove heater core from heater housing
1 - Install heater core in housing.
2 - Position heater unit and install attatching nuts.
3 - Connect water drain hose and defroster hose
4 - Connect blower motor wire
5 - Connect and adjust damper door control cables
6 - Connect heater hoses
7 - Refill coolant
8 - Check heater for proper operation.