George,
I don't have an answer but can sympathisze as mine does the opposite, i.e. locks but will not unlock the main door. When I use the fob or the key code to unlock, the interior lights come on and I hear a click, but nothing. There is 12v power at the contacts when locking and unlocking.
I too am not doing anything until I get to a different climate although mine is indoors and warm - to get it looked at I would have to take it someplace that may or my not be able to diagnose it and i dont want to do that now. I expect when I get south there will be more opportunities and people that can diagnose the problem.
Jeff