Breaker panel & circuit wiring question

Hi All, we’ve owned a 1995 Funlite 23FLL since new. I’m doing some maintenance/upgrades, including re-doing 120V wiring to the fridge. The trailer came new with a 6-breaker panel (for the 120V system). From Hi-Lo, the refrigerator’s 120V heating element circuit was wired in with the same breaker as the transformer/12-V charger, and I want to re-wire things so the fridge has its own dedicated breaker. That way, I’ll be able to turn-off the charger/transformer without shutting off the 120V fridge heating element.
Here’s the breaker panel wiring scenario -- six breakers, left to right ( see pic here https://1drv.ms/u/s!Au56qY7L6bswnpkXff4N6tYvRowQgQ?e=h4qvpP ).
Breaker#1: green 30A: Main panel shut-off.
Breaker#2: red 20A: A/C only (dedicated outlet).
Breaker#3: red 20A: Connected to a Romex cable, but cannot figure out what it’s to!
Breaker#4: red 20A: All five 120V plug-in receptacles, except A/C and fridge.
Breaker#5: red 20A: Fridge and 12V-transformer/charger.
Breaker#6: blue 15A: Open/un-used, not connected to anything.

My question is about 20A Breaker#3. Hi-Low wired it to a Romex cable (same as all the other breakers, except #6 which isn’t wired at all) that runs down the left side of the trailer to...somewhere.
I’ve traced the Romex cables, but without completely tearing out the floor and all panels, I can’t see where it goes. I’ve removed several wood panels to see routing. I traced/mapped all the breakers and their circuits, but can’t find out what this #3 breaker/cable goes to or what it does.
Here’s what #3 is NOT connected to:
-Fridge (3-way),
-Battery charger/12V transformer,
-Water heater (propane only),
-Furnace (propane+12V only),
-A/C,
-None of five 120V receptacles, including the one outside the trailer,
-Range (propane only, no electricity),
-Pump, fans, waste/water/toilet/monitor, etc. (all 12VDC stuff)
-TV antenna amplifier/booster (12VDC)
-Hydraulic lift system (12VDC),
-Solar panel/system (add-on from the dealer).
There is nothing in my original Funlite Owners Manual in terms of a 120V wiring diagram (in fact, it shows a 4-breaker panel, not a 6).
Can anyone suggest what this breaker/cable goes to? Generally if a breaker is un-used, then it’s not wired/connected to anything, period.
Has Hi-Low wired this for something else? I’d like to use this 20A breaker for my dedicated fridge circuit, but would first like to know what/if Hi-Low had wired it to.
I appreciate any input and sorry for the length of this post

If everything works when you have that CB off, I'd say it's not connected to anything. Possibly, it was installed for a 120V/Propane water heater, or, a microwave? If you pull on the wire, does it seem to be connected to anything at the "hidden" end?

If you can't find anything it feeds, just go ahead and pull the existing wire out of it and replace it with the Fridge wire. You won't hurt anything by doing this, but you can always replace the existing wire if something suddenly doesn't work.You could also replace the 15A breaker with a 20A one, and run the Fridge through that.

- Jack

Jack, your suggestion of a microwave circuit led to the answer. That sent me searching... and in the little cabinet under the range, tucked waaaay in the back, there's a 120V outlet I'd never known existed. Because of its close proximity to the range it's got to be for Hi-Lo's microwave option (we got the gas oven instead). Indeed, said outlet is assigned to CB#3. Thanks Jack!

Yippee! I'm so glad you solved the mystery! So, you could either use the #3 breaker, or, you COULD still replace the #6 breaker with a 20A one (they are easy to replace) and use it. But, at least you know what the #3 breaker is for.

- Jack

Good one guys, that must be what my extra breaker if for. I also have the stove with oven.

Jack, I'm going for re-assigning the fridge to CB#3. It'll be a quick easy job, just switch a couple Romex connections. In ~25 years of ownership, 120V power from the outlet-of-Atlantis has yet to tapped, so I don't think anyone will be missing it
But maybe!...I just might re-assign the hermit outlet to the empty 15A breaker, for whatever reason.