2012 Jeep liberty blowing cold air as well as heater when heater is turned on

I had the tiniest Rad Leak in my 04' Liberty, it was so minuscule I had no clue it was happening until my heat stopped producing hot air. I changed my water pump back 8 months ago, and re filled the coolant at that time, when my vehicle stopped producing hot air the Rad was almost dried up but the Jeep had not over heated or showed any other signs of over heating.. Check coolant levels and your Rad.

I have all of the above and everything checks good but still no heat.

Just replaced water pump and still no heat. Was told it had air pockets. They flushed them out and heat was awesome, but now I'm losing heat again after a few days, so will be taking it back for another flush. Was told if the next flush fails, will need to replace heater core. I initially had a substance added to help unplug what was thought to be a plugged heater core. By the time I brought it back for first flush, water pump was making noises so they replaced that and went from there.