The 2000 Ford Focus uses an evaporator core to cool the air that is sent into the cabin when the air-conditioning is engaged. The evaporator core contains Freon gas that cools the air that the air-conditioning fan blows across it, on its way to the cabin. Evaporator cores can fail over time, most commonly due to leaks. You can tell that your evaporator core is malfunctioning or has failed completely if you notice that the air suddenly stops blowing cold from the air-conditioning vents.
Lift the hood of the car and locate the battery's negative terminal. Use a socket wrench to remove the ground cable from the negative terminal. Locate the two heater hoses on the firewall -- these hoses run directly into the heater core. Place a drain pan underneath the hoses (slide the pan beneath the car) to prevent antifreeze from leaking onto the ground and then disconnect the heater hoses from the firewall.
Lower your steering column and remove the instrument panel assembly. With the instrument panel assembly removed, disconnect the steering column shaft from the steering column and then steering-column-to-body fasteners. Use a screwdriver to remove the dashboard front trim panels.
Remove the center console panel (use a screwdriver to remove the screws that line the perimeter of the panel) and then pull the panel away, exposing the firewall box. This box contains the evaporator and heater cores. The evaporator core sits beside the heater core and is surrounded by a seal. Pull the evaporator core out and remove it from its seal.
Insert the new evaporator core into the seal and then slide it back into the firewall box. Reassemble the center console panel and reattach the dashboard front trim panels. Reassemble the instrument panel assembly and reconnect the steering-column-to-body fasteners. Reconnect the steering column shaft to the steering column and then raise the steering column.
Reconnect the evaporator and heater hoses through the firewall and reattach the battery's ground cable. Close the hood and run the air-conditioning on the coldest setting for fifteen minutes to ensure that the new evaporator core is functioning properly.
