Can you get some pics from the back of the coop....
...and inside the run, specifically the framing under the HC?
Where in MI are you north, south, east, west?
You need 24/7/365 ventilation.
How many birds in there?
What kind of winter?
Where in this world are you located?
Climate, and time of year, is almost always a factor.
Please add your general geographical location to your profile.
It's easy to do, and then it's always there!