We picked up the FR3 on Saturday afternoon and the dealer assured us that the AC had been running for several hours that day. It was certainly nice and cool inside. It took us about 30 minutes to get the RV to the storage place, and the AC ran the whole way so we are feeling good about the current repair work. It was over 100 degrees outside and relatively humid as well. We don't have plans to take it out again for several weeks to really challenge the system, but we both are confident that this ordeal is done.
I'm not 100% sure about how it was done, but here is what some of it sounded like to my ears. They hardwired the AC that was on the RV with a 10-something wire, and connected it to a dedicated 20 amp circuit. It was working fine.
Rather than try to rewire the entire RV, they took the suggestion of a friend of ours who has a luxury coach and who does a lot of his own improvements like LED lighting, and put the AC on a single 20 amp circuit rather than one that was shared as FR had done it. Our friend suggested that having the 2 operating circuits so close to each other could be generating extra heat that was causing the circuit to trip. There were 2 unused spaces for circuits. From what I understand this kind of work should have taken less than an hour and cost under $20.
Fingers crossed all of the kinks have been worked out and it's all fun from here. If you feel like you need a better explanation about what was done, send me a private message and I'll have my husband explain it to me again.
Again - thanks to everyone who contributed to this conversation, and I hope that our experience has been helpful to some of you. Now we get back to posting pictures of beautiful places and dogs having fun.