2012 Jeep Liberty vents smell like anti freeze when heaters on only! No Leaks, just flushed, new thermostat, no water...

Dallas it could also be the heater core has a small pin hole and needs to be replaced, same thing happened to my 2012 jeep liberty. It took me about 8 hours to pull the entire dash to replace it! are you getting any smell of anti freeze or oil film on the windows? If so it is potentially the issue. But first check the blenddoor actuate as mentioned. Hope this helps..

Take the two hoses near the fire wall to the heater core off and flush it out, make sure to flush out in reverse, so as not to push obstruction further into the heater core. Take a water hose and flush it out till clear of obstruction