I had the same problem this spring. Called the 2 local Ford dealers, neither would do it due to size. (Actually was a bit of a relief as one of the Ford dealers has a parking lot that’s annoying to navigate in a car!)
I ended up taking to a local Freightliner facility. When I called ahead the Service Manager was good in saying if it was mechanical, should be an easy fix. If electrical, probably best to not have his techs chasing it due to their lack of Ford knowledge, basically said “they would eventually fix it, but might be trial and error and not the most cost effective”.
Prior to my appointment I ended up jumping the low pressure switch which confirmed either the switch was bad or it was low on refrigerant. At the time I noticed the switch assembly turned easily in my hand, which isn’t normal and hopefully a cause of the leak.
Tech vacuumed out the system, tested it to ensure it held pressure, and then recharged with refrigerant and dye so that if leak wasn’t the loose low pressure switch, it could be traced. So far so good, bill was about $200 for labor and refrigerant.
If it is a bad low pressure switch, they are pretty cheap and can be ordered by any Ford dealer. (I bought one just in case as the Freightliner dealer wouldn’t have stocked and was fine with me buying and them installing if needed). Switch was about $25, and mine needed a supplemental wiring pigtail which was another $30. Ford took the unopened ones back when I didn’t need.
2015 Winnebago Vista 35B. "The Vistabus!!"