RV Fridges used to run on LPG, 120VAC, and had a "keep cool" 12VDC mode. Most newer ones, even 1990, are more likely to be LPG or 120VAC.
BUT!!! EVERY RV fridge requires 12VDC for its control functions. It will NOT cool on ANY source if it doesn't have 12VDC to the electronic controls.
I tried to find the dimensions of a 3804 and couldn't. If it's the typical "8 Cubic Foot RV Fridge" it's about 24" wide 24" deep and about 60" tall. If so, you can replace it with a "residential/apartment" fridge for under $200. Very little trim work required to fit it in. Then all you need to do is find a way to keep it closed on the road.
But that's best when you plan to go to campsites that have electric power to plug into. It'll hold cold for a day's travel if you don't keep opening it, and being compressor driven it'll recover fast once you set up at the campground. And yes, you can use one without a power source if you use Solar/Batteries/Inverter and/or a Generator.
RV fridge is pretty much three major components:
1. The Cabinet (doors, shelves, gaskets, etc.) - Think of a big Ice Chest
2. The Cooling Unit - all that piping stuff on the back
3. The Controls - Circuit Board, Wiring, Interior Panel.
If you can troubleshoot it, replacing the Controls or Cooling Unit will get you cold for half cost of a new RV fridge or less. Not cooling and Cabinet damaged, Replace. Cooling Unit AND Controls bad, Replace. Bad Cooling Unit and you can DIY the replacement, around $600. New RV Fridge (8-cft) nearly $1500.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB