Pete,
Is this the Dometic air unit that came with the "I-Feel" remote? Do you know or can you find the paperwork on the model number for the AC unit.
I'm pretty sure there are conversion kits to convert your control system to a more traditional and current control system.
That said, it may cost you $300 or more. With your unit being nearly 14 years old, you might be better off buying a new AC unit that comes with the updated control system.
The newest control systems use a 3 conductor wire - so you might get lucky and not have to run a new wire to a wall thermostat.