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It was not unusual for older RVs to have , manual by-pass for high draw items. To control total power use.
An older Komfort 5er I had there was a wall switch to change the power supply from the A/C to the microwave outlet.
You couldn't use both at the same time.
Other units I've seen, by-pass the electric side of the water heater, to power the A/C.
EDIT: A couple of things I see in the photo. The wire with the white cap appears to be attached to the C/B with a second wire. ( 2 wires connected to one C/B) and the wiring entering the bottom of the compartment, I see black and white hooked up, but no ground, and a grommet around the wires instead of a clamp, like the blue clamps on the wiring entering from the rear. These are not good wiring practices. Not to code.
Any chance the A/C was not a factory install?
I can't get enough resolution on the picture to be sure, is the wiring through the bottom of the compartment , aluminum or copper?
Looks like aluminum in the picture while the rest is copper.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.