One of the problems with AC in caravans is managing performance expectations. Most cars now have AC and if you expect to get similar cooling performance in a caravan you will be disappointed.
The biggest restriction in a caravan is the availability of electrical power to run it, In a caravan at best you have a 16A supply which if it were all used for the AC would give you a power input of 3.6kW. That would leave nothing for any other electrical appliances. So most caravan AC manufacturers limit the maximum input power to 2kW or less and also have reduced settings.
Caravan AC units utilise a compressor based system, and will usually have a coefficient of performance (COP) of around 2.5 This means for every Watt of input energy it will move 2.5 Watts heat. This is good an why heat pump technology has some great potential forspace heating and cooling.
Buckmans unit has a 4A consumption that is only 920W. With a COP of 2.5 that gives a total cooling capacity of only 2.4kW This is great, but in reality it's not a lot of cooling, and this is where expectations are often not met.
Not many Brits have AC at home, so they have a limited experience most often of how a car system performs. In a car the AC unit is usually driven by a belt from the engine. It will of course depend on the make and model, but its not uncommon to find the AC will use 5 to 8 Horse power (= 8 to 11kW) of power to drive it. Again applying the COP of 2.5 means the system in a car may be able to provide between 20kW to 27kW of cooling. That almost 10 times as much as the caravan unit. - though to be fair the AC does not run continuously in most cars it is thermostatically controlled and may run for about 50% of the time , but thats still 10 to 14kW.
Now consider the volume inside a car the AC is expected to cool. IN some SUV's you might have 4cu meters. so that gives power to volume ratio of 2.5 to 3.5 kW/m3.
In a 4.5m long caravan you will have a volume of about 16.2m3 and a cooling capacity of at best 2.4kW that's only 0.15kW/m3 or 6% or less of the capability of the cars system!
However the job in a caravan is slightly differnt, The ratio of surface area (both wall and glass) to volume is better than a car, and teh level of insulation is also probably better so the need for an AC may be reduced compared to a car. And using the caravan AC you may find you want to selectively cool some areas more than others, and it has to be said that many caravaners do find AC works well enough for them and improves comfort in hot weather.
Just don't expect ice cubes to be frozen at the AC's nozzels.
