Lack Of Cold Air Returns In The House Cause Poor Results From The Air Condition Unit.any Idea?

During the summer two of my bedrooms on the far northwest side of the condo are not as cool as the rest of the house. Could it be that there are no cold air returns in those two rooms, or the unit isn't large enough to force air that far away. I have the same problem in the winter. Those two rooms are cold if you keep the door closed at night. I don't understand why this could be. The condo is only three years old.