We invest in air conditioning to enhance comfort at home or in the vehicle. The temperature range we perceive as comfortable is not really that wide, as the illustration shows. Temperatures up to 26°C are only obtained when humidity is low. When the air is damp, the thermometer should not exceed 20°C. We feel more comfortable when the room temperature is between 18°C and 22°C and the humidity is between 40 and 70%.
To create these conditions in a motorhome the air must be cooled down and dehumidified at the same time. This calls for a compressor powered RV air conditioner. A/C systems based on direct or indirect evaporation cooling are less effective.