I shut the unit down for about an hour to replace the drain hose
connection. When I restarted, all was fine! I guess there was some
icing. Never encountered that before in all the years I have been
using this dh (since 2008) but the cellar was quite cold when it was
first turned on (which it always is.) Also I have a transparent drain
hose and the dh seemed to be functioning just fine through all this
despite the icing. Also a mystery as to why the icing would have
caused "actual' humidity to read incorrectly high.
More penance I suppose...should have noticed the icing right
away!
(Thanks all for your help!)
Frank