Sounds to me like this:
Heater control valve is screwed up, stuck closed, or the heater core has been bypassed due to a leak.
(heater cores can be a bear to change on our vans.)
It could be a bad ground, but I'd have to look at a wiring diagram to figure that one out.
I'd find any common grounding points, then bypass them to see if the problems stop.
Use the manual with the wiring diagram in it (that you bought from Issue 2
) to find the color designations to the wires.
That would be how I would approach your issues.
(I love the wire on the ash tray starting trick