Misted up caravan windows

Hello.

I am hoping someone may know of a solution to "blown" or "misted" windows. I have read somewhere that the little sealing bungs can be removed and the condensation allowed to dry either naturally or by applying heat. Then when unmisted replacing the bung. My windows only mist up when warmed by sunshine. Are the windows sealed units as at home or are they just full of dry air. Any advice welcome. My Coachman Caravan is now 10 years old and this is the only problem it has developed..   Any advice will be appreciated.

Thanks.