I have a 2010 dodge journey sxt (fwd). I have little heat on the driver side, but ok on the passenger side. not great, but ok. in mild weather, it's fine, in cold Canadian winter....not so much. I've had the heather core replaced aug 2017. the heater actuator and thermostat replaced dec 2016. what else could be wrong?

 

Your HVAC blend doors are not working properly. I have the same problem in my Ram 1500. I am replacing my heater core and while I am in there, I am changing all of my blend doors. Lots of work, but it is worth it. My driver's side blows cool, while my passenger side is hot. Take a look at this video. There are 4 parts, so you can go to the later ones where he changes the blend doors. I hope this helps.

DDay77