Cellar Humidity Problem

Is it a new freezer? If not I'd say it's getting a bad seal. What temperature are you keeping it at? How long have you been running freezer for

 

You shouldn't have moisture in there unless outside air is getting in. I used to have a beer fridge that got mold in it from a bad seal at the bottom of door. If you leave door open to long you can also get moisture problem. But I'm by far no expert just an idea

 

First step would be to make sure there aren't any leaks as recommend above.

Does the freezer have any sort of drain or pan by the coil? If it doesn't, I honestly don't know how you'd ever get humidity to reduce because there isn't any place for the condensate to get out of the freezer when it forms on the coil. I'm thinking that even a non-defrost freezer might have one though because it needs some way to defrost the coil itself so that air can move through the coil.

If there is any sort of drain by the coil, or for folks who are using refrigerators and have the same problem, I'd recommend increasing the deadband. Beer doesn't need to be kept at exactly 55F and by using a small deadband (especially if the fridge isn't very full) the coil doesn't run long enough to really get enough condensate on the coil for it to drip off and out of the fridge. Instead the water stays on the coil and just re-evaporates back into the air inside the fridge. Same thing applies to any cycling air conditioner if it's oversized (and a freezer coil is oversized for a cellar).