Proline Freezer runnung all the time?

My Proline upright freezer runs all the time. Just recently the temp gage moved well into the green. A couple of days ago I turned on the Rapid Freeze function and the gage is now showing just on the yellow. Also I have noticed that the side of the unit is very warm/hot to touch (500mm from base close to the door). Any ideas what's going on? The Freezer is located in quite a confined cupboard space at the top of the cellar steps. I think the unit is well over ten years old.