We had the evaporator replaced in our 2008 Liberty in 2015, it was leaking freon. They replaced the heater core as well while they were in there b/c they didn't want to go back anytime soon. Real PIA job, I stopped by during the repair and they had everything from the front seats forward to the firewall/cowl out.

While the evaporator looked dirty with dust, lint and maybe some plant material on it the heater core that they took out looked clean and could very nearly pass for new. There were just a few small blemishes on the aluminum surface. Now I'm in TX and the heater didn't get used all that much.

If you are getting hot air on one side and not the other it sounds more like an air distribution problem instead of a core issue. JMO. Good luck, oh, and your cost to repair was comparable to mine.