When it comes to replacing your old Atwood system I recommend The Advent Air RV Air Conditioner - 13,500 Btu - Black # ACM135B.
This AC unit lets you replace an existing AC or add a new AC to your RV or camper, it will work with your existing Advent Air, Dometic, COleman Mach, or Carrier air distribution box and thermostat. Can be paired with a Coleman Mach or Carrier setup using a wiring adapter (# ACCOLKIT, # ACCARKIT - sold separately).
The AC has a black, hard plastic cover that... view full answer...
As your motorhome already has a 7-Way # PK11898 it will likely already have a converter on the motorhome. I have included a image of the pinout on a 7-way so you can verify if the tail lights are already converted. A Test Light # PTW2993 can be used to test the wiring.
If you determine the lights are still separated I recommend installing the Upgraded Heavy Duty ModuLite Circuit Protected Vehicle Wiring Harness # C59496 before the 7-way. This will get you to a standard 7-way wiring so... view full answer...