If so equipped, have the air conditioning system refrigerant discharged and recovered by an air conditioning technician. Disconnect the cable from the negative battery terminal. Drain the cooling system. Disconnect the air conditioning evaporator lines and note the drain tube at the firewall. Plug the ends of line fittings going to the rest of the A/C system to prevent contamination. Disconnect the heater hoses from the heater core tubes at the firewall. Remove the instrument panel. Disconnect and remove any harnesses fastened to the heater/air conditioning unit that would hinder its removal. Remove the mounting fasteners for the blower and evaporator housing, then lift that section of the heater/air conditioning unit out of the vehicle, ensuring not to damage the seals for the condenser lines and the evaporator drain tube. Remove the mounting fasteners for the remaining heater/air conditioning unit section and then lift it out of the vehicle. Remove the cover that secures the heater core tubes. Take out the heater core. When reinstalling the heater/air conditioning unit, ensure that the evaporator drain tube is correctly positioned through the firewall hole. Connect all electrical connectors on the heater/air conditioning unit before repositioning the instrument panel. Reconnect the heater hoses in the engine compartment. Reconnect the battery. Refill the cooling system. If equipped with A/C, have the system evacuated, recharged, and leak-tested by the technician who initially discharged it.