Coleman Electric Evcon outside air intake?

Quick question about the outside air intake for a Coleman electric Evcon unit in a modular home. Is this something that is absolutely necessary?

Here is why Im asking, the room where the unit is located is always much colder than the rest of the house, whether the unit is running or not. Up until a few weeks ago I contributed this to the horrible door and a window in that room. I have replaced the door with an insulated metal door and added a insulted storm door. Also, I removed the window and insulted the opening from the window in the room as well. I completely remodeled the exterior of the house, all new windows doors and siding, even house wrap which it didn't have before.

Anyway, I have sealed and insulted every nook and cranny I can find but the room is still a lot colder than the rest of the house. That's why I'm asking about the fresh air intake on this unit. I cant figure out where the cold air is coming from other than there. Should there be some type of flap in the duct work so it is only open when the unit is running? I would have to get on my roof, which isn't a problem, to see if there is one in there or not. Replaced the roof a year ago and it seems as though there isn't one in there but that's been over a year, so I could be mistaken.

Anyway thanks for the help...

Ben