Removing and replacing the heater core in your 2003 Ford Taurus is not an easy task. The core, which acts as a small radiator, is installed within its housing near the firewall behind the instrument panel. In addition to removing the panel, the heater housing is sealed shut with numerous levers and springs that must be removed.
Discharge the air conditioning system at your Ford dealer's service department or an automotive air conditioning shop.
Disconnect the car's negative battery cable.
Drain the engine coolant into a large container at the radiator's drain plug--you may need pliers to remove the plug--then drain the remaining coolant at the engine block drain plug.
Remove the instrument panel from inside the car--this will involve removing the center console, stereo, heater/air conditioner controls, steering column and trim panels. Pull off the vent screen from the passenger side cowl.
Loosen the clamps for the heater hoses with pliers and disconnect them from the core's tubes; these are mounted on the firewall within the engine compartment. Plug the tubes with rubber plugs.
Remove the mounting screws for the white, rectangular-shaped blend door actuator with a hex screwdriver, unplug its electrical connector and remove it from the air conditioner evaporator.
Disconnect the spring on the heater core cover using a small, flat head screwdriver on the spring's hooked end. Depress the locking ramp and remove the short lever on the temperature control door shaft using the same screwdriver, then rotate the door shaft downward and remove the metal link at the lower end.
Remove the three small mounting screws on the heater core cover with a hex screwdriver, lift the lever up and remove the cover and its gasket from the housing.
Pull the heater core from the housing.
Remove the foam seal from the old heater core and transfer it to the new one then insert the replacement core into the housing.
Close the cover to the heater core housing using the three screws, close the door shaft with its metal link, the locking ramp and the spring.
Reconnect the blend door actuator to the evaporator housing with its screws and reinstall its electrical connector.
Unplug the heater tubes at the firewall and reconnect the heater hoses with their clamps.
Reinstall the entire instrument panel and its components in the reverse order of removal.
Reconnect the negative battery cable and refill the cooling system; use a fresh mix of water/antifreeze if the old coolant is contaminated.
Evacuate and recharge the air conditioning system at the same location that it was discharged.
