water, water heater and fridge help

[us2xlr8]

1. Water heater serial # c583140 model 6avr from american appliance mfg I have no idea if it works or holds water. How do I fill and operate it or check it out? 2. Fridge serial # 308273 says Marshall-Argentina for cold star need to know where the 12v dc wire hooks up to. There are 2 screw type connectors what look like connectors on back but which one is + and - nothing is labeled. Last owner disconnected power converter and all dc appliances found diagram for converter. Tested converter it works surprisingly, just need to be careful for bat boil over. 3. How do I get water in holding tank. I don't see any water hook up, I do see what looks like a cup that slides out, Do I add 1 pitcher at a time. And how do I sterilize. This is a 1978 Cavalcade 22ft TT.
Thanks for any help and advice you can give.

[jesilvas]

Most likely that is a pilot model water heater. You have to have propane on, and light the pilot at the WH, then turn it to on and it will light the main burner as needed. To get water in it, you hook up to city water or turn on your water pump and run a faucet. There may be valves bypassing the tank on the back (inside of coach) that might have to be turned just right.
Those 12VDC wires hook up at the + and - connections at the back.
There should be a mouth or spout opening to pour water into the tank. Just stick the hose in there.

[us2xlr8]

I see conections on back of fridge but not marked, just afraid to reverse polarity. What would happen if polarity was reversed to fridge?

[jesilvas]

Thought you said it was marked.
Follow the wires. One should go to the board, the other to a metal ground.