The diesel heat didn't work in the aft cabin. Dave thought maybe it was the rear thermostat. Sure enough when he replaced it, it started working. But a while later it stopped. Dang. He sits down to dinner. In the middle of dinner he leaps up - "must be the relay under the master bed!". Sure enough there it was - a loose connection. That was obvious right? Everyone would know it was the relay under the master bed? Not so much...