You'll have to be more specific as to the model/year of the vehicle. The expansion valve in the older vehicles was mounted inside the heater/cooler box up against the evaporator core; no interconnecting pipes between the evaporator and the expansion valve.
On the newer vehicles the expansion valve is bolted on to the evaporator lead pipes thru a grommet; again no interconnecting pipes between the evaporator and the expansion valve.
Replacing the expansion valve on the older vehicles is very difficult as the heater/cooler box needs to be removed for access. On the newer vehicles you might be able to replace the expansion valve on the engine side of the firewall although I've never done it so don't quote me.