I am wondering if anyone knows why when I cook the windows all fog up the air exchange is on has never been serviced( not sure how)I live in a 10 year old minihome...

During the cooking process, particularly with gas burners, a lot of water vapor is released. In winter, the water vapor condenses on the cold window surfaces producing water. If you do not have a direct vented hood, you are just recycling the water vapor around. Living in a mini home aggrevates the situation since you have a small area volume and the interior relatie humidity must get pretty high.