Couple of things. First off, are the constructs Coldbloods or Chillbloods? It's Chillblood in the Chill Scattered entry, but Coldblood in the template itself.
Also, it says that the crystal from the brainfreeze ability doesn't melt in a minute if the victim has the cold subtype. Does it ever melt? If not, it seems a bit powerful, since it means that any cold creature that gets a critical hit from a coldblood is going to succumb eventually. I would have it lose its effects after a minute and a half or two minutes.