The component most people think of as "the AC"

The rooftop unit removes heat from inside the RV and releases it outdoors to cool the interior. Heat pump models can also provide supplemental heating in mild temperatures. 

Common Types

• AC only 
• Heat pump: Cooling and supplemental heating
• Low-profile: Lower overall height, helpful for clearance concerns
• Standard profile: Traditional overall height 
• Fixed speed: The compressor runs at one operating speed
• Variable speed: Adjusts the speed of one or two compressors to match cooling demand (think "RV mini split")

Not all replacement RV air conditioners will work with existing components. It is always a good idea to confirm compatibility with current thermostats, control boxes, ceiling assemblies, or any other components before purchasing. A quick compatibility check can prevent a very expensive mistake. 

The interior vent panel mounted on the ceiling

The ceiling assembly, or air distribution box (ADB), distributes cooled or heated air into the cabin. 

Common Types

Ducted: 

• Connect to air ducts to distribute air in multiple rooms/areas
• Common in larger RVs or fifth wheels

Non-Ducted: 

• Blow conditioned air directly into the living space
• Common in smaller RVs and campers

Additional Differences

Some ceiling assemblies/ADBs may include: 

• Manual controls
• Electronic controls
• Washable filters
• Adjustable airflow features

Ceiling assemblies are not always interchangeable between different brands or system types. However, if you want to switch from one brand to another, some brands offer conversion kits that allow their rooftop unit to be used with another brand of ceiling assembly. 

Controls how and when your system operates

The thermostat communicates with the system and tells it when to cool, heat, or cycle off. Some models also communicate with compatible furnace systems. 

Common Types

• Wall-mounted: Mounted on the wall inside the RV
• Remote controlled: Operated using a handheld remote
• Single zone: Controls one area (or "temperature zone")
• Multi-zone: Controls multiple rooms / areas (or "zones") independently (ducted systems only)

Compatibility matters more than appearance. Two thermostats that appear to be identical may be designed to support two completely different system types. 

The "brain" of the system

The control box, or "controller", helps rooftop units, thermostats, and other HVAC components communicate with one another.

Some controllers may support: 

• AC only
• AC and heat pump functions
• Heat strips
• Furnaces 
• Etc.

Some systems include a pre-installed control box within the rooftop unit or the ADB, but others require a separate control box to be purchased and added during installation. 

When replacing an existing control box or starting over with a brand new system, it is important to check compatibility with all other components to ensure your system operates correctly. 

Supplemental electric heating

Heat strips are an add-on electric heating element for AC only systems to provide additional warmth in cooler temperatures. 

Unlike heat pumps, heat strips do not transfer heat through a refrigeration cycle. 

Heat Strip vs Heat Pump

Heat Strip: 

• Add-on device that adds supplemental electric heat to a compatible AC only system

Heat Pump: 

• Rooftop unit designed to provide cooling and heating using a refrigeration cycle
• Can be more efficient than heat strips

Both heat strips and heat pumps are intended to supplement heating in cooler weather rather than to completely replace the need for a furnace. Either one can be a great way to reduce propane costs in colder months, and some people find them sufficient as standalone heating in mildly cool temperatures.