If the Air Conditioner on your Caravel
is an Armstrong Bay Breeze it is very likely to be either a facotry or Airstream dealer installed unit. Air Conditioning was an available option on Airstreams for a number of years when your Caravel
was produced - - my '64 Overlander had an Armstrong Bay Breeze from the time it was new - - it was really nice with its wall-mounted thermostat control. When my Bay Breeze was deemed beyond practical repair, I went with my Airstream dealer recommended Coleman, but lost the wall-mounted thermostat control as well as the condesate drain pan.
If you are fortunate enough to find that you have an Armstrong Bay Breeze that is repairable, I think that you will find that it functions every bit as well as the modern units - - I actually think that mine cooled a bit more effectively than my new Coleman.
Good luck with your investigation!