Coolant level is good. Rear blows cold at all times, no matter what setting the heater control is on. Front heater works well.
2006 Nissan Pathfinder rear vents only blow cold air. The front blows hot fine. on 2006 Nissan Pathfinder
sounds like you have a problem with the hot/cold damper door or motor, in the the rear heater control. This will not be an easy repair for the DIY, if you have not done many car repairs.