Well, not sure if that is it but it sounds like it to me. The lines can freeze. The filter should be in your main intake. Check it really well. Not just the filter...the whole area. Let it sit and thaw a few days. Then try not to run your house at fucking snow temps!
How old is the unit? Last serviced? May be time for a good clean out and run through. Couple hundred clams well spent.
I'm not a tech....just quite a bit of experience with them. Plus, that whole Holiday Inn Express thing.