[Bernard Feltzer]

It could be a few things.
Low cooling fluid level, air pocket in system, burp it.
Water pump impellers may have corroded away, unlikely unless you have almost 200,000 miles on van.
Radiator may have a leak in it internally, I don't know if that model year has the tranny cooler built inside the radiator. Once the tranny fluid and radiator fluid co-mingle, you might as well junk the van.
2005 models have problems with the upper cooling connection that goes to radiator failing.
If you have rear heat, check the plumbing under van to see if the metal tubes rusted out.
Metal bypass pipe from water pump are known to rust away.
Check the radiator cap.
If your van has many miles on it, maybe the heater core is shot already.
There are many posts about these new vans having stuck flap doors and blinking lights, something about a self diagnosis procedure.