Download SUBJECT: New HVAC Sub-Assembly Replaces Blend Or Recirc Door Components MODELS: 1999 – 2004 (WJ/WG) Grand Cherokee (All Markets) New HVAC sub-assemblies are now available in the Mopar Parts system. Each new sub-assembly consists of several individual components. The new sub-assemblies improve component reliability. It is recommended that the respective sub-assembly be installed if a blend air door(s), a recirculation door, a door link, or a sub-assembly housing requires replacement. The following table provides the part numbers for the new HVAC sub-assemblies.