Late '80s Central vs. Roof Air

[Greg York]

I am trying to understand how "Central" air conditioning is implemented in the late '80s coaches. Where is the ducting? Where are the air units located? I am making the assumption that this might be a quieter system than the
roof mounted units. Are there any drawbacks to the central air system? For instance, can an older roof unit be replaced with a commonly available off the shelf unit today? What is the availability of replacement parts or units used in the central air system, by comparison?

[TechTalk]

This is a pretty wide ranging question, but we'll offer some discussion as thought starters. The central air units installed in the 80s were "split systems," with the condenser and compressor units installed in the belly areas, and the evaporators installed upstairs, blowing cooled air directly into the interior. Typically, little or no ductwork is used. The noise levels are comparable to roof units. An advantage of central air is the clean roofline, giving the coach a nice, tidy appearance. A disadvantage is increased maintenance, partially because of connections for the freon lines that run from the underfloor compressor/evaporator units and the evaporators upstairs. In addition, availability of repair parts have become a problem after some 15 years, while roof airs are virtually self-contained, allowing an entire obsolete unit to be easily replaced with a current model. It is not very practical to replace an older roof air with a central air unit, although not necessarily impossible. Simply a question of time, effort, and money.