Why do freezers frost up? And how do I prevent it?

Just last week I vacated all food from my freezer, grabbed a blowdrier and got to work. By the end, nary an ice particle was in sight. Good!

Today a quick look in the freezer reveals a half-inch cover of snow-frost progressing quickly to ice-frost. What causes frosting, anyway? Why is this happening so fast? What can I do to stop it?

Notes on my fridge: I’ve just moved in here. It has one door, and then a little freezer compartment up at the top with its own plastic door inside.

It’s condensation. Everytime you open the freezer air rushes in. When it does it carries humidity in with it which condenses on the freezer walls (shelves, food) and freezes leaving you with frost. Same concept as a dehumifier, or the water that drips under your car on a hot day when you’ve had the AC running. In large commercial coolers and freezers they have to go into a defrost mode several times a day to prevent a giant block of ice from forming on the evap coils and restricting air flow. Actually most home refridgerators and freezers do it as well, it’s just a little more subtle.

Oh, one more thing, I don’t know what type of freezer you have, but DON’T go picking at it with a screwdriver or ice pick unless you really know what your doing. In small (dorm type) fridges where the ‘freezer’ is just the top part surround by what looks like heavy sheet metal with a maze type pattern in it, the freon runs through those grooves. Also in some the freon runs behind the walls. If you puncture those with a tool it’ll probably be cheaper to buy a new fridge then to get it fixed. It’s also not going to be very fun to end up with a face full of freon.

If that little plastic door doesn’t seal well, the freezer compartment will suck moisture out of the fridge compartment. That’ll give the rapid buildup you’re seeing.

Guilty. :smack:

Everyone above is correct as to the causes of this problem.

Aside from making sure that the little freezer door closes tightly, the only thing I can suggest is using a bag of dessicant in the freezer to absorb the water out of the air before it freezes. This has worked fairly well for our freezer, but you do have to change the dessicant periodically. Additionally, it will only prevent buildup on the inside of the freezer, not on the outside (if that matters to you). Any good hardware store will have some.

mischievous