Defroster won’t blow hot

[Bcoley]

2016 ram 2500 diesel

Cannot get hot air to come out of window defroster. Change the setting for the air to come out the dash vents and only warm air comes out of passenger side, cold air on driver side. I changed the engine thermostat. The dealership changed a heater core on it last winter. Has somebody changed the hot cold blend door on these things and are they located under the dash where I need to take it out?

Any help would be appreciated

 

[NETim]

Could well be a blend door actuator. Lots of YT videos on replacing them. If I remember right, there are 3 on the manual systems and 4 on the climate control versions.

The blend doors are plastic and they do break.

 

[mtnrider]

100% a Clogged heater core. Extremely common on these trucks. You can try and back flush it but may end up replacing it.(yes I know you replaced it but it's clogged again) Blend doors were an issue on the 3rd gens, not so much on the 4th gen HD trucks