[xythobuz]

that's really just physics. warm air gets in through the opened door, after closing it rapidly cools down, because air does not hold that much heat energy. Because it cools it contracts, which reduces the pressure inside the freezer, causing the outside air pressure to hold the door shut more firmly.

No electromagnets or anything.

[ziml77]

And it's a demonstration of just how much cold air is falling out when the door is opened. While less convenient, a chest freezer will do much better at holding the cold air even when opened.

[technothrasher]

While visiting rural northern Namibia, a Damara tribesman I was talking to asked me where I was from. Upon hearing that I was from a cold Northern part of the world, he commented that it must be great that half the year I didn't need to run my freezer.

I just stared at him, not knowing what to say. He stared back at me for a while and then started laughing. Then I realized he was screwing with me, and I just said, "Touche'".

[em-bee]

if that were the case then i should be able open the door right after i closed it. realistically, even a pump could not be that fast. electromagnets sound like a much better explanation. simple logic too. whenever the temperature is higher than expected, turn the magnets on.