Adding a 2nd RV Roof Air Conditioner

I am interested in installing a second air conditioner in my fifth-wheel where the vent currently is located in the bedroom upstairs. I know I have a breaker in the box marked “2nd air conditioner,” but I’m not sure if I can actually install one there. Could you please advise me on what I need to look for to make sure I can install one before I buy.
Jim, (Augusta, GA)

Jim, your coach is apparently pre-wired for that second roof air conditioner as is evidenced by the presence of the second circuit breaker in the panelboard distribution box. If you remove the inside garnish (trim) piece from around the 14-inch roof vent at the ceiling, you should find a hole through one side of the cutout opening. There’s no need to remove the vent itself from the roof for this inspection; you’ll be able to verify this from the inside.

Chances are there is also a flat, blank cover plate near that side of the ceiling right across from the vent opening. Inside that ceiling box you should find pre-installed conductors routed up from near that second circuit breaker. Chances are the Romex is not actually connected to the circuit breaker yet, but it should be evident within the enclosure. Whoever installs that second roof A/C will have to route a short section of Romex cable from that junction box in the ceiling over to the 14-inch rough cutout. The new A/C mounts right over the existing hole where the vent is now. Once you’ve established there are indeed conductors for the air conditioner present in the ceiling, the roof vent can be removed and the air conditioner installed. Another step in the procedure is to connect the Romex to the circuit breaker and the neutral and ground busses in the breaker box. A quick check of the voltage at the new air conditioner should be the final step before firing up that new cooler.