A: To remove the heater core, start by disconnecting the cable from the negative battery cable and draining the cooling system. Then, disconnect the heater hoses from the heater core inlet and outlet pipes at the firewall and plug the heater core pipes to prevent coolant spillage. Next, remove the entire instrument panel. For manual transaxle models, unbolt the shifter bracket and move the shifter assembly aside. For automatic transaxle models, remove the control cable from the shifter, disconnect all wiring from the shift assembly, and unbolt the shift. For all models, remove the large duct from the front of the heater unit, the heater core cover, and the small plastic cover from the heater core pipes. Finally, remove the heater core by pulling on the end tanks. To install, simply reverse the removal steps and reconnect the cable to the negative terminal of the battery before refilling the cooling system.