What would be the reason your rear heat wouldn't work in your 1998 Pontiac Montana but the front does work back makes noise but no heat produced or even air Fuses have been replaced?
usally there is a valve. Should be in the collant line that goes to the back heater. So when you turn on the heat it opens the valve to let the collant into the back heater and then closes when you shut off the rear heat. follow the heater lines from the back and see if there is a valve hope this helps !!!!!!!!!!!!!!