Those are vents that can be open or closed to adj. the humidity in the unit.
On the dial type of thermometer it can be checked in a glass of crushed ice. Ice melts at 32 deg F so when the hand settles it should be at 32. If it is not there is a hex at the top of the stem that you can gently grasp with pliers and then holding that fast you can turn the dial till it is set to 32.
On the dial type of thermometer it can be checked in a glass of crushed ice. Ice melts at 32 deg F so when the hand settles it should be at 32. If it is not there is a hex at the top of the stem that you can gently grasp with pliers and then holding that fast you can turn the dial till it is set to 32.