Yes, it sounds like you have the factory air. Is there a fan switch in the rear overhead? Is it on? First I'd check the refrigerant pressures as I suppose it's possible there isn't enough to reach to the back of the van, but since the front is working fine, I would suspect there is a thermostatic expansion valve in the rear that controls refrigerant flow through the rear evaporator. If there is an expansion valve, you might give it at tap with the handle of a screwdriver of some other softer tool.
Agile Ride improvement package