Need help 2000 Cirrus heat problem

Hello, so my sister was on her way back from seattle today and she was 30 miles outside of Spokane and her temperature gauge redlined. I drove out to her and the thermostat was bad so i told her take it slow and drive with the heat on, so i got it home and now she has no heat? i replaced the thermostat and drove around the block to raise the temperature to mid level on the gauge and it blows semi-cold air. any ideas what this is and how i can fix it?
Any help would be great
thanks
Ryan

Check for water in the oil. On many of the Mopar engines of this era the timing chain drives the water pump. When the water pump goes out it dumps water into the oil.

You may have filled it up and it emptied into the pan without you knowing it.

Might be an air pocket.Most have a bleeder to let the air out.Rocky

thanks for the help, i flushed the radiator today and loads of sand and other particles came out and that seems to have fixed the heat and overheating problem but now she is leaking coolant from the passenger side of the engine thinking freeze plug? how hard are those to replace and/or is there anything online i can find to help my attempt?

thanks again
Ryan