If you are saying that when you flip the fan switch from on to auto that the fan still stays on when the AC is off then I’d say that somehow you wired the “auto” AC fan switch to a “hot” wire. The auto fan setting is basically an off switch for the fan when the AC compressor is not operating. If u tried two different thermostats and it still stays on, then both the on and the auto fan settings are getting power all the time. The auto side should only get power when the compressor is running.
The wire connections from the thermostat to the AC unit are located up in the ducting inside the coach. It is accessed by removing the inside panels of the AC unit. You do not have to remove the outside roof cover. You cannot access them from there. There is a box up in the ducting where the wires from the thermostat connect to the AC unit. However, since this problem occurred after fooling with your thermostat, the thermostat wiring is probably the issue.
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