Q: How to replace an evaporator core in an air conditioning system on Ford Expedition?
A: On some models, special spring-lock coupling tools are required to release the connectors used on the refrigerant lines throughout the air conditioning system. There are different special tools for each line size; these tools can usually be found at local auto parts stores, often in a set. The evaporator core is located inside the same housing as the Heater Core. Before replacing an evaporator core, determine for certain that the core is leaking by having a leak test performed with special equipment at dealer service department or automotive air conditioning repair facility. The cover to the heater/evaporator housing needs to be removed, which requires the removal of the instrument panel. Whenever the evaporator core is replaced with a new one, the accumulator/drier will also have to be replaced. Disconnect the refrigerant lines at the firewall. Pull the evaporator core from the heater/evaporator housing. Installation is the reverse of the removal process. Add three ounces of new refrigerant oil to the accumulator/drier inlet tube when a new evaporator core is installed. Also, before the lines are reconnected, it's a good idea to replace the orifice tube. On some models of Navigator/Expedition vehicles, there is an optional heat/air-conditioning system located behind the left-rear interior trim panel. The assembly includes a blower, heater core, and evaporator core. Removal and installation procedures are similar to the procedures for the standard evaporator core up front, although the rear unit is much more accessible. Have the system evacuated, recharged, and leak tested by the dealer service department or an air conditioning repair facility.