Sub Zero Freezer Vacuum

Question

The whooshing vacuum sound no longer happens when I close the freezer drawer. Is this costly to fix. If so can I let it go, it's a 15 year old Sub Zero.Thanks

I just started having the same problem with my side-by-side, plus there is ice around the light and near the left-top part of the freezer compartment. I vacuumed the dust out of the top and cleaned away all of the ice. The freezer still doesn't make the swooshing sound that seals the door and the ice is back. Over the summer we had freon put in and a new thermostat installed. Any ideas.