The Ford Expedition was originally introduced by Ford in 1997 to replace the "full-size" Ford Bronco. The Expedition is considered a "full-size" sport utility vehicle, and remains popular with the automotive community even though it generally gets poor gas mileage. The Expedition's sister car, the Lincoln Navigator, is basically an Expedition with a "dressed-up" front grille, vehicle interior and a higher price tag. Replacing the heater core in the Ford Expedition requires moderate automotive-repair knowledge.
Disconnect the negative battery cable from the vehicle battery.
Locate the drain petcock on the bottom of the vehicle radiator.
Drain the engine coolant from the vehicle radiator into an empty container using pliers and turning the petcock counterclockwise. After the coolant is drained, close the petcock completely.
Remove the instrument panel that is above the steering wheel. The heater core cover will be visible.
Disconnect the heater-core hose clamps using pliers and compressing the clamps, making them larger, then slide the clamps to the center of the two heater-core hoses. Pull the hoses off the heater core by hand and label the hoses by marking "top" on the top hose and "bottom" on the bottom hose with a marker.
Remove the retaining screw securing the air-conditioning plenum "adapter," using a Phillips-head screwdriver and turning the screw counterclockwise. Pull the plenum "adapter" by hand, to the right until it is completely removed from the plenum. Set the plenum adapter aside.
Disconnect the vacuum line from the plenum chamber.
Remove the two heater-core brackets off the plenum chamber using a socket wrench and socket and turning the two bracket bolts counterclockwise until the bolts are fully removed. The brackets can then be pulled off by hand.
Locate the top of the plenum chamber. It is separated from the bottom part of the plenum chamber with 13 screws.
Remove the top of the plenum chamber using a socket wrench and socket and turning the top plenum chamber screws counterclockwise. Remove all 13 screws. Pull off the plenum chamber top by hand.
Remove the heater core by pulling up on the heater core by hand, removing it from the bottom plenum chamber.
Push the new heater core down inside the bottom part of the plenum chamber, making sure the two heater-core hose connection tubes come out of the left side of the bottom plenum chamber. There are two holes in the bottom plenum chamber for the heater-core hose connection tubes.
Install the plenum chamber top using a socket wrench and socket and turning all 13 screws until the plenum chamber top is fully tightened.
Place both heater-core brackets back on the heater-core plenum chamber and tighten the two bolts using a socket wrench and socket and turning clockwise until the bolts are fully tightened.
Connect the vacuum line back onto the plenum chamber.
Push the air-conditioning plenum adapter back into the plenum chamber by hand and secure it by turning the screw clockwise with a Phillips-head screwdriver.
Push the two heater-core hoses back on to the heater-core hose connection tubes by hand, making sure the "top" hose goes back on the top connection tube and the "bottom" hose goes back on the bottom connection tube. Squeeze the clamps with pliers to make the clamps larger, and move the clamps down the hoses to the heater-core connection tubes and release the clamps to secure the hoses onto the connection tubes.
Install the instrument panel.
Fill the radiator with the vehicle's specified amount of a mixture of engine coolant and water.
Connect the negative battery cable to the vehicle battery.
Start the vehicle engine and turn on the heat.
