The icing problem was a strange one in the movie. Did he leave critical components exposed so that they could freeze? Icing is a problem for aircraft because it causes drag which counters the lift of the wings. Ironman on the other hand is propelled by force like a rocket. The weight of the ice would have to be greater that the thrust could overcome.
Anyway, in theory yes the suit could be frozen. In theory all matter can be frozen at absolute zero, the point at which matter stops moving. But then the suit wouldn't matter because Connor would be frozen solid on the inside as well. But there is also other factors. If encased in ice how much would be the point where the armor could no longer break the ice, essentially becoming immobile. But that also depends on how solid the ice is. The more solid the less ice is needed.