N-B question about generaor & a/c's & panel

[Gearheadzs]

I know this post is way old, but I wanted to add a little to it, as I had a very similar issue, and this may help someone down the road.

My issue was that my 3rd ac, which is in the BR, would not come on, though the LR and Garage would. I got the error code E7 on my 3rd AC. During my investigation, after switching the breaker a few times, killing all power on circuit breaker and house power, trying just on genny power, testing GFI's and fuses, etc, I turned to the AC itself in the BR.
I removed the cover, and took down the control box in it. A #2 phillips for all. I then opened the cover where the romex goes into the box and as I touched the neutral wire (white), it just slipped out of its wire nut. Yay I thought that surely was the problem, the neutral likely just vibrated out, so I removed the cap, reinstalled both neutrals and went and turned on the thermostat to fire it up, thinking for sure this solved the problem. Nope, got the hourglass for a minute or so, then the error E7 code again. Damn.
Not to be deterred, I got my meter out, and checked the breakers in the breaker box for 120VAC, all good and all fuses (even though there are dummy lights, its an RV), again all good. I removed and reconnected the data cables, in the thermostat, and the AC itself a couple times, then checked the romex into the AC-- Nothing, no power..
I looked at the neutral connections to the neutral bus bar and tightened, all looked good, and double checked the Breaker, good as well. I started thinking, what did I do, perhaps I ran a screw in the wall that may have opened the circuit, but I had not been working in any area where this would have happened. So I slept on it.
This morning, after running it through my head and preparing for worst case scenario of running all new romex to it, I decided first to strip and reconnect all romex at the AC andbreaker panel. Especially looking at the neutral.
When I pulled the neutral out of the bus bar, it looked tinny, not copper colored where the screw on the bus bar locked it in place. So I stripped it and reconnected it. His the thermostat, and she fired right up. BAMN!! Fixed.

My thoughts as to what happened. I believe when the neutral was vibrating out of the wire nut, it caused some arcing or over heating in the neutral at the breaker panel bus bar, and lost its good connection. By stripping it and reconnecting it, solidly at both ends, I removed the issue. Similar to too much corrosion on a battery terminal causing voltage issues.

I know this was long winded, but I saved myself a grip of time and money by thinking it through and trying my repairs step by step to isolate the problem, it worked, and now we can hit the road next week with all AC's ready to go as needed.

I hope this helps you if you run into this issue.

Gear.