Why Moving an AC Breaker Causes Backfeed on a 50A Split-Phase RV

[FiveOclcok]

Howdy y’all,
I have a 2026 Grand Design Imagine RV where I recently installed an inverter. The RV is a 50-amp split-phase system. Since I installed the inverter on the black L1 leg, I decided to move the converter over to the red L2 side and move the air conditioner which was originally on L2—
over to L1 so that I could run the air conditioning while the inverter is operating.
Moving the converter breaker did not appear to cause any issues. However, when I moved the air conditioner breaker, something strange started happening. While the inverter is running, the air conditioner circuit seems to backfeed 120 volts to every breaker in the panel.
I cannot figure out how this is happening. The converter normally plugs into an outlet on the back of the breaker panel. I traced that wire and it is only about six inches long and is not touching anything. Yet somehow that outlet is still showing 120 volts, even with the breaker turned off and the converter unplugged.
At this point, it seems like I cannot move either the general breaker or the air conditioner breaker to the other leg of the panel, even though both are supposed to be 120-volt circuits.
Is there any chance the air conditioner could actually have 240 volts going to it, with only one leg protected by the breaker? That would seem unusual, but I cannot figure out why I’m getting this kind of feedback when I move the breaker from L1 to L2 for either the air conditioner or the general circuit.
Any insight would be greatly appreciated.

 

[John From Detroit]

Sounds like a bad neutral somewhere. Check all neutral leads and connections.
Split phase inverters... No longer made but I'm sure others can do this.

My first inverter was a Xantrex Prosine 2.0 2,000 watts single phase.
But if you had two you plugged a data cable into the proper port one end on one one on the other and it was now a split phase 120/240 volt system (Common neutral) Proprly phase locked to each other.

As I said they no longer make the Prosine. but I'm sure someone makes a pair like that.

 

[Gary RV_Wizard]

Please explain more about how you "installed the inverter on the L1 leg". Do you mean the inverter receives 120v from L1 to pass-through, or that you are feeding the inverter output to the L1 bus? It seems like it has to be the latter if the a/c on the L1 is going to receive power. Was it your intent to power all the L1 breakers from the inverter, or only the a/c? If only the a/c, you need ti isolate the a/c breaker from L1 and put it on a separate bus that is inverter-only.

Also, what model inverter is it and does it include pass-through capability?