Do you have forced air heat? (Or whatev it's called...)That happened to us in Denver -- cold cold brrrrr hair one night. There was a broken switch (zero recollection of its name?) and apparently is common. Was cheap/quick to fix -- wishing the same for youuuuuuu.
Thank goodness we're here and it doesn't really get below 50! I sure hope he comes soon! I bet that is it.