Larry,
The units on your Vantare should have been 13,500 btu cool-only with heat strips. What a lot of rv facilities are doing now is not stocking the cool-only because most people would seem to rather have them. Also, since the introduction of the 15,000 btu units, they tend not to stock the 13,500's for the same reason. The main difference in a 13.5 and the 15 is that the LOW fan speed is really the medium windings of the 3-speed motor they use for the fans. On the 13.5 you had, all 3 fan speeds showed up on the CCC and were in-fact utilized, allowing you to actually select low for the quietest operation. By the way, Dometic does STILL offer a cool-only, and you can still get an "add-on" heat strip kit for them. The fan and blower squirrel-cages appear to be the same, but Dometic did go to a molded plastic housing, where they previously utilized sheet metal (galvanized) with a foam insulation on the interior of it. I presume a combination of both changes are responsible for the increased db levels you are experiencing.
Ben Cummings
U.S.A. Luxury Coaches, LLC
Clearwater, FL