I have a 2013 2500, 165k miles and the heater never gets hot, warm but not like it should.
I've flushed the core with radiator cleaner and CLR, (minimal trash removed).
Replaced both blend doors located behind the radio/center console (no change).
Has anyone else had this issue?
I believe there is another blend door behind the glove box area, could that be the cause?
I'm trying to stay away from replacing the core.