A: To remove the front heater core, start by disconnecting the cable from the negative battery terminal and draining the cooling system. Then, remove the Coolant Reservoir and disconnect the heater hoses at the heater core inlet and outlet pipes on the engine side of the firewall. Unscrew the heater core cover and carefully cut along the top edge to remove it. Finally, remove the heater core retainers and detach the heater core from the housing. For the rear heater core, begin by having the air conditioning system discharged. Remove the left rear quarter trim panel and the upright air duct from the housing. Disconnect the electrical connectors to the HVAC housing and remove the cover to the housing assembly plumbing from under the vehicle. Remove the heater and air conditioning hoses and the mounting nuts to the housing assembly. To install both heater cores, simply reverse the removal steps. Refill the cooling system, check for proper operation, and recheck the coolant level.