Hey murph welcome to the forums.
Is the heater not blowing hot air the only issue, are all fans speeds working and all other controls from that panel working. There have been a number of people suffer problems with the resistor behind that panel, it usually causes more problems than just the heater blowing cold air though. For most it's also been a warranty job too which is some relief given the price Nissan think they can charge for the 2 cent resistor.