Welcome to iRV2.
Do you know what brand of dash A/C unit is in your coach . Evans or Denso ?
Expansion valve is usually where the liquid and suction lines ( yellow arrow )connect to the housing holding the evaporator .
Blue circle in this picture of my Evans unit .
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.