What is the difference between ducted roof air and non ducted.

Ducted A/C has an internal fancoil unit installed in the roof space of the home. From this central location, a series of ducts run from it and into as many rooms in the house as the owner desires. From these ducts, this allows you to cool or heat each room individually – called zoning
Split systems stand out for their relatively low initial purchase price. Another perk is that the installation is not so invasive – it can often be done in a day or less from a licensed technician. Though, being that the unit is fairly small, it is best suited to cooling or heating one room – this is either a positive or negative depending on how you look at it. On one hand, it’s an efficient option if you only need to cool or heat one room, but on the other hand they are less effective in larger spaces. Rarely could a split system air conditioner cool or heat an entire home. Split system air cons are great options for small areas, but lack the power to affect larger spaces – this is reflected in their relatively cheap purchase price, from around $1,000-$2,000.

The air conditioners on RVs are 110 volt AC. They do not run on 12 volts and should not be run on inverters. You would need at least a 2000 watt generator, preferably 3000.
If you have the power, it requires cutting a 14 inch square hole in the roof. The air conditioner is clamped down by 4 bolts from the inside, part of the internal control package. You would need what is called a "non-ducted" inside unit which would have the thermostat and control knobs.

Ducted unit or straight blow through ?

If no element installed and connected, heat setting will not work.

Sounds like the issue is simply condensation inside the exhaust pipe where it passes through the un-heated attic space. If you use the shower and the exhaust fan, lots of humid air is passing over the inside surface of a very cold duct, then running back down to your bathroom ceiling. You could get any non-specialist handyman to wrap insulation around that duct in the attic. But you can mitigate the problem by running the fan for a few minutes before you start the shower (thereby pre-heating the duct before you give it a blast of moist air) , and leaving it run for 20 minutes afterwards (thereby drying out the duct after use). Regarding the discolored ceiling, the handyman can apply some stain-covering white primer too.

Yes it is a sealed unit, and there are some refrigeration guys who can solder on valves and recharge, but make sure you get a quote first, as some charge as much as a new unit. That said, I'd be looking at evaporator coils/fins as well as condenser coils and fins for dirt and debris and give them a real good cleaning. I'm going to assume this is a ducted ceiling, so Make sure your getting flow through all those ducts, and check for how cool it is. Does it feel like cooler air coming out the ducts? Rule of thumb is 20 F difference between ambient and discharge should be normal. All that condensation tells me it's trying to cool but you may have a problem elsewhere, like plugged fins, or faulty ducting. If the flow coming out of ceiling ducts is not good and cool, try removing the ceiling assy and see if the discharge side is cool there, and check that the ducts in to the ceiling have no obstructions as well and are properly aligned.Let me know what you find. Make sure return air filter is clean as well and get a flashlight and look way up in the return area, at the fins for dust collected on fins etc. If you remove outside cover on roof, turn off breaker, and you can use a hose to spray down and a nylon brush to clean fins and coils at condenser. Watch for bees, or wasps when you remove that cover on the roof.

The upper unit doesn't matter ( the actual ac unit on roof ) it's the lower control unit (inside at ceiling) that you need to change to use either ducted or non-ducted system. Any RV dealer can supply that, probably have it on the shelf. Just make sure you write down the model number and serial number, off the bottom of the upper unit, so they can match lower unit to it, for ducted system.

Heat is only supplied through floor ducts, as hot air tends to rise up to ceiling to create circulation of hot air inside the car, same way cold air (AC) is only supplied through roof ducts as cold air tends to settle down.

go to www.luxurymetals.com
there are many good high quality vents on the site

Is this a non-ducted system with dials to turn on it, or is it controlled by a wall thermostat ?