A couple of folks have reported the "K" being frozen shut in really cold
climates.

I can't recall any posts regarding cracking of the firebox, though.

You might want ot search posts at the Kamado forum at (kamado.com). You could
even call the factory but it might take a few tries to get a person...if you
just leave a message, it's doubtful that you'll get a return call.

Steve