We invest in air conditioning to enhance home or vehicle comfort. The temperature range we perceive as comfortable is not really that wide. Temperatures up to 78°F/25°C are only obtained when humidity is low. When the air is damp, the thermometer should not exceed 68°F/20°C. We feel more comfortable when the room temperature is between 64°F/18°C and 72°F/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.