The expansion valve on a 2003 Dodge Durango is
not located in the rear. The expansion valve (or metering device in some cases, depending on the specific A/C system) is part of the air conditioning system and is located
under the hood, within the engine compartment, near the evaporator. Its exact location will vary slightly depending on the engine and specific A/C system configuration. You'll likely find it near the firewall or on one of the A/C lines.
To pinpoint its location, you'll need to consult a repair manual specific to your 2003 Dodge Durango's year, make, and model (including engine size). A Haynes or Chilton manual would be helpful. You can also find diagrams online, but use caution and ensure the diagram matches your vehicle exactly.
