Your problem has three sources. 1) Humidity too high in camper. This can result from introducing humid air from outside, cooking, breathing, showering. 2) Insufficient air movement through the A/C and, (3) Too low a temperature setting. Think of the sweating glass model. The more humid it is - the more it sweats, the colder the glass - the more it sweats, put the glass in front of a fan -the less it sweats.
So, to reduce, but probably not completely eliminate the problem, do the following:
Keep the doors, windows and vents shut. Reduce the introduction of humidity from cooking, showering, etc. Raise the temp setting a bit and keep the fan on high and on continuous run. Look to achieve a balance between the above.
Happy Camping! ///// Richard D.
2006 4x4 Ford 250 SD / 2007 Flagstaff 827 FLS
One very patient wife and one furry child who travels with us. Forty-two years of trailering and camping, and I still have a blast.