Hmm...if they were moist/moldy smelling, I wouldn't water them at all.....especially if they got a chill...water is probably the last thing they are looking for when they're in "conservation mode" from being stressed out. 2 hours at 20F might be enough to cause their bodily water molecules to freeze and lyse. I would provide a lot of warm humidity but not water, and keep the roots exposed to as much air as possible. My happiest orchids are the ones that are doing the Full Monty, roots hanging out naked as jaybirds. Of course, I say all this, without knowing what kind of orchids they are! Can you post what they are and take pictures of them?