Very doubtful it's an Espar on a 1999 Dodge SMB. It's likely a Suburban.
OP, look on the outside of the van for a small plate with a couple of holes in it, usually printed Suburban (brand) or possibly Atwood. This is the exhaust for the furnace. It will be on the inside in this same location, about a 1x1' grill in a cabinet somewhere in the van.
The fact that this isn't obvious to you leads me to believe you probably don't have one. Not all do.
Another way you could find it is to find the thermostat in the van and turn it on. Whether your heater is functional or not the fan will probably still come on leading you to the furnace.
Is there a thermostat? If no thermostat then no furnace.