if you have air conditioning in your jeep and its still working, during the winter months you still need to run the system to keep it from drying the seals out. with an air conditioner system if you are running the heating system in the winter and recycling the air from within the vehicle, you will get a build up of moisture within the cabin
If you think about it everytime you get into your jeep on a cold day your screen mists up cos of the water vapour in your breath hits the cold glass and condenses. so to reduce the vapour you need to do the same thing as you do in the summer, run the heater but allow the heated and moist air to escape from the cabin by having a window open a few mm