To find it definitively, you should:
* Consult your owner's manual: This is the best resource for the specific location on your van.
* Look under the van: Carefully inspect the area near the fuel tank. The canister is usually a cylindrical container, often made of plastic, with various hoses connected to it.
* Use a repair manual: A Haynes or Chilton repair manual for your specific year and model will have diagrams showing the location of the EVAP canister.
Be aware that accessing the area under the van might require jacking it up and using jack stands for safety. Always prioritize safety when working under a vehicle.