Why is the air coming in and not going out? Is it always the same or does it get worse when it is colder?
Ask yourself this question. Why is the air entering my house through my kitchen exhaust vent? Now, if you don't know why, then its time to research. First, read up on the chimney effect. Then ask yourself how you can remedy the problem. Knowledge is key. To fix, first you need to understand. Good luck.
You have to fight through some bad days to earn the best days of your life.